Discussion:
OT: Converting miles/km
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Christian Weisgerber
2024-09-19 23:12:52 UTC
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I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.

So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).

WHAT?

Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.

If nothing else, it's faster to type on a calculator.

I think that's hysterical.
--
Christian "naddy" Weisgerber ***@mips.inka.de
Aidan Kehoe
2024-09-20 05:07:19 UTC
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Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
The old units were completely neglected when I went to school, which is
unfortunate, it’s routine that we need to convert between vulgar feet and
inches for height to centimetres in daily life, or between vulgar stones and
pounds to kilograms. What I learned from my father (born 1945, went to school
before it was neglected) was that a kilometre is 5/8 of a mile, which helps in
converting the speed limit signs in Northern Ireland to what my speedometer
shows.

I will attempt to bear ln(5) in mind going forward!
--
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)
Garrett Wollman
2024-09-20 17:43:01 UTC
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Post by Aidan Kehoe
Post by Christian Weisgerber
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
pounds to kilograms. What I learned from my father (born 1945, went to school
before it was neglected) was that a kilometre is 5/8 of a mile, which helps in
converting the speed limit signs in Northern Ireland to what my speedometer
shows.
That's the approximation that's much easier for mental arithmetic, and
similarly, 8/5 when converting the other way. Otherwise, 1.609344 is
the exact conversion, and 1.609000 is good enough for almost every use
(unless you're doing weird stuff like survey miles, which are based on
the old foot of 1200/3937 meter,[1] rather than the "international"
foot of 0.3048 m).

However, an approximation that has actually proved useful to me is
that 1 m/s ≅ sqrt(5) mi/h. As everyone knows, sqrt(5) ≅ 2.236068, or
2.2 if you only need two significant figures, which is much easier
to remember than 3600/1609.344 ≅ 2.236936.

-GAWollman

[1] One will note that this conversion defines a meter to be exactly
39.37 inches, although that's never how it's actually phrased.
Sometimes that's a more convenient conversion than the modern one even
if it's no longer exact.
--
Garrett A. Wollman | "Act to avoid constraining the future; if you can,
***@bimajority.org| act to remove constraint from the future. This is
Opinions not shared by| a thing you can do, are able to do, to do together."
my employers. | - Graydon Saunders, _A Succession of Bad Days_ (2015)
Steve Hayes
2024-09-21 02:35:35 UTC
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Post by Aidan Kehoe
The old units were completely neglected when I went to school, which is
unfortunate, it’s routine that we need to convert between vulgar feet and
inches for height to centimetres in daily life, or between vulgar stones and
pounds to kilograms. What I learned from my father (born 1945, went to school
before it was neglected) was that a kilometre is 5/8 of a mile, which helps in
converting the speed limit signs in Northern Ireland to what my speedometer
shows.
My rule-of-thumb is that a kilometre is 0.6 of a mile. The instrument
in the car showed tenths, rather than eighths of a mile.
Post by Aidan Kehoe
I will attempt to bear ln(5) in mind going forward!
It doesn't work in reverse?
--
Steve Hayes from Tshwane, South Africa
Web: http://www.khanya.org.za/stevesig.htm
Blog: http://khanya.wordpress.com
E-mail - see web page, or parse: shayes at dunelm full stop org full stop uk
Hibou
2024-09-20 05:22:28 UTC
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Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
Afflict? Sometimes I wonder how many more times I'm going to hear
Germans criticising how we do things.
Post by Christian Weisgerber
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
I'm afraid I don't see the problem. Just assign 1.609344 to a memory
cell. That's what I do. A shortened version is fine for mental
arithmetic - better than ln(5) - and if one has forgotten 1.6... but has
a calculator, what's wrong with tapping 2.54 x 12 x 5,280 / 100,000?

Simples!
Hibou
2024-09-20 06:26:26 UTC
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Post by Hibou
I'm sorry, I don't know where to post this.  I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
Afflict? Sometimes I wonder how many more times I'm going to hear
Germans criticising how we do things. [...]
Thinking about that, it occurs to me that I have allowed myself to
criticise how other nations do things - the Americans, the French, and -
yes - even the Germans.

I withdraw my remark.
Peter Moylan
2024-09-20 08:00:27 UTC
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Post by Hibou
I'm afraid I don't see the problem. Just assign 1.609344 to a memory
cell. That's what I do. A shortened version is fine for mental
arithmetic - better than ln(5) - and if one has forgotten 1.6... but
has a calculator, what's wrong with tapping 2.54 x 12 x 5,280 /
100,000?
That's all very well if you can remember that there are 5280 yards in a
mile. I'm afraid that my school days are far behind me, and Ancient
History was one of my weakest subjects.

I'm still just hanging on to the fact that an inch is about 25 mm, but
that's probably the magic number that's next to fade from my memory.

I still remember that a mile is about 8/5 km, but it's unlikely that
I'll ever again visit a country that uses miles, so that too will soon
fall into the bin for useless facts.
--
Peter Moylan ***@pmoylan.org http://www.pmoylan.org
Newcastle, NSW
Hibou
2024-09-20 08:43:15 UTC
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Post by Peter Moylan
Post by Hibou
I'm afraid I don't see the problem. Just assign 1.609344 to a memory
 cell. That's what I do. A shortened version is fine for mental
arithmetic - better than ln(5) - and if one has forgotten 1.6... but
has a calculator, what's wrong with tapping 2.54 x 12 x 5,280 /
100,000?
That's all very well if you can remember that there are 5280 yards in a
mile.
<Cough>
Post by Peter Moylan
I'm afraid that my school days are far behind me, and Ancient
History was one of my weakest subjects.
I'm still just hanging on to the fact that an inch is about 25 mm, but
that's probably the magic number that's next to fade from my memory.
I still remember that a mile is about 8/5 km, but it's unlikely that
I'll ever again visit a country that uses miles, so that too will soon
fall into the bin for useless facts.
SI is all very well for science, and BTUs and the like give me the
heebies, I admit; but Imperial units - ounces, pounds, inches, feet,
miles, are often well adapted to everyday life, and live on in a largish
chunk of the world. The whole world (as far as I know) uses knots and
nautical miles in the air, and on and under the sea. So, quite recent
history, then.

Where Britain has gone wrong is in metricating half-heartedly. We drive
for miles, and then fill up in litres - yet milk mostly comes in pints
and quarts. Tables of clothing sizes are sometimes in inches and
sometimes in centimetres (and probably inaccurate anyway). And so on.

We should be champions in mental arithmetic - though the evidence is
that we're not.
occam
2024-09-20 05:51:30 UTC
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Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
You do use Google search? Try typing '1 mile = ? kilometers' in the
google search bar. Answer = 1.60934.

P.S. The google search bar has come a long way. It can be the source of
a lot simple-ish maths solutions, thanks to rudimentary AI.
Bertel Lund Hansen
2024-09-20 08:54:06 UTC
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Post by occam
You do use Google search? Try typing '1 mile = ? kilometers' in the
google search bar. Answer = 1.60934.
You don't even need the "? kilometers".
--
Bertel
Kolt, Denmark
Hibou
2024-09-20 09:09:45 UTC
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Post by Bertel Lund Hansen
Post by occam
You do use Google search? Try typing '1 mile = ? kilometers' in the
google search bar. Answer = 1.60934.
You don't even need the "? kilometers".
The calculator in Ubuntu knows all sorts of conversion factors.

If one selects 'Miles', the default conversion is to Parsecs.

Better make sure the battery's charged.
occam
2024-09-20 09:46:00 UTC
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Post by Bertel Lund Hansen
Post by occam
You do use Google search? Try typing '1 mile = ? kilometers' in the
google search bar. Answer = 1.60934.
You don't even need the "? kilometers".
Yes you do, unless you want to choose one of: 1760 yards/1.60934 kms/320
rods/1.70108e-13 light-years etc. There is more to a mile than kilometers.
Bertel Lund Hansen
2024-09-20 10:06:03 UTC
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Post by occam
Post by Bertel Lund Hansen
Post by occam
You do use Google search? Try typing '1 mile = ? kilometers' in the
google search bar. Answer = 1.60934.
You don't even need the "? kilometers".
Yes you do, unless you want to choose one of: 1760 yards/1.60934 kms/320
rods/1.70108e-13 light-years etc. There is more to a mile than kilometers.
Of course. It was understood that you wanted kilometers - as you wrote.
--
Bertel
Kolt, Denmark
Peter Moylan
2024-09-20 10:51:02 UTC
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Post by occam
Post by Bertel Lund Hansen
Post by occam
You do use Google search? Try typing '1 mile = ? kilometers' in
the google search bar. Answer = 1.60934.
You don't even need the "? kilometers".
Yes you do, unless you want to choose one of: 1760 yards/1.60934
kms/320 rods/1.70108e-13 light-years etc. There is more to a mile
than kilometers.
Yes, but Google doesn't give you those unless you ask for them. It
assumes that you want kilometres.

But maybe it's country-dependent, because it didn't even give me the
American spelling. Perhaps in the UK the default is set to rods, poles,
or perches.
--
Peter Moylan ***@pmoylan.org http://www.pmoylan.org
Newcastle, NSW
occam
2024-09-21 06:37:36 UTC
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Post by Peter Moylan
Post by occam
Post by Bertel Lund Hansen
You do use Google search?  Try typing '1 mile = ? kilometers' in
the google search bar.  Answer = 1.60934.
You don't even need the "? kilometers".
Yes you do, unless you want to choose one of: 1760 yards/1.60934
kms/320 rods/1.70108e-13 light-years  etc.  There is more to a mile
than kilometers.
Yes, but Google doesn't give you those unless you ask for them. It
assumes that you want kilometres.
But maybe it's country-dependent, because it didn't even give me the
American spelling. Perhaps in the UK the default is set to rods, poles,
or perches.
No, alas, the default choice of Google _is_ kilometers. But it can be
made to change its mind if enough of us ask for the miles to light-years
conversion.
Christian Weisgerber
2024-09-20 11:52:50 UTC
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Post by occam
You do use Google search? Try typing '1 mile = ? kilometers' in the
google search bar. Answer = 1.60934.
My point wasn't really to give practical advice on unit conversion--
I assume we can all manage--but to laugh at the sheer absurdity of
two entirely unrelated numbers working out to approximately the
same, purely by chance.


PS: I use Google for currency conversion.
--
Christian "naddy" Weisgerber ***@mips.inka.de
Helmut Richter
2024-09-20 09:30:37 UTC
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Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
... the English-speaking world with the exception of Ireland, Canada,
Australia, New Zealand, and South Africa and some others.

I think the term “United Kingdom and USA” would have been shorter and
slightly more accurate.
Post by Christian Weisgerber
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.

I like much more those thumb rules that actually allow you to estimate orders
of magnitude, e.g.:

1 year ≅ π · 10⁷ sec ≅ 31415926.54 sec

or

1 year ≅ √10 · 10⁷ sec ≅ 31622776.60 sec

or, only for those wanting more precision, the arithmetic mean of the two
which has three leading digits correct.

--
Helmut Richter
Bertel Lund Hansen
2024-09-20 10:10:53 UTC
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Post by Helmut Richter
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I haven't neede it, but just for fun I have calculated the Danish speed
limits in miles. If you want round firgures, it's:

50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
--
Bertel
Kolt, Denmark
Phil
2024-09-20 10:40:44 UTC
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Post by Bertel Lund Hansen
Post by Helmut Richter
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
I'm not sure how common this is, but the speedometer in my car has
scales for both mph and km/h, so in principle I don't need to convert.
In practice, though, I have the above table in my head, from the old
days. It's easily remembered because the right-hand column corresponds
to the usual preferred values for UK speed limits.
--
Phil B
Silvano
2024-09-20 13:51:47 UTC
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Post by Phil
Post by Bertel Lund Hansen
Post by Helmut Richter
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
I'm not sure how common this is, but the speedometer in my car has
scales for both mph and km/h, so in principle I don't need to convert.
In practice, though, I have the above table in my head, from the old
days. It's easily remembered because the right-hand column corresponds
to the usual preferred values for UK speed limits.
And the left column corresponds to the usual preferred values for speed
limits in Continental Europe, AFAIK.
You should add 30 km (reduced speed in some parts of cities) and 120 km
(seen from time to time).
Bertel Lund Hansen
2024-09-20 17:11:22 UTC
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Post by Silvano
And the left column corresponds to the usual preferred values for speed
limits in Continental Europe, AFAIK.
You should add 30 km (reduced speed in some parts of cities) and 120 km
(seen from time to time).
That would be 30 mi (two much) and 75 mi.

[on purpose]
--
Bertel
Kolt, Denmark
Stefan Ram
2024-09-20 15:37:43 UTC
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Post by Phil
I'm not sure how common this is, but the speedometer in my car has
scales for both mph and km/h, so in principle I don't need to convert.
These days, even regular folks can afford small computers at home,
and with a BASIC interpreter, anyone can whip up his own conversion
program. The programming language BASIC is so simple that anyone
can pick it up. It can handle math terms straight out of the box.

MILES.BAS

10 PRINT "MILES TO KILOMETERS CONVERTER"
20 PRINT "-----------------------------"
30 INPUT "ENTER MILES: "; M
40 K = M * 1.60934
50 PRINT M; "MILES ="; K; "KILOMETERS"
60 END

TRANSCRIPT

MILES TO KILOMETERS CONVERTER
-----------------------------
ENTER MILES: ? 2

2 MILES = 3.21868 KILOMETERS
Sam Plusnet
2024-09-20 19:05:17 UTC
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Post by Phil
Post by Bertel Lund Hansen
Post by Helmut Richter
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I haven't neede it, but just for fun I have calculated the Danish speed
         50 km = 30 mi
         80 km = 50 mi
       110 km = 70 mi (2 km too much)
       130 km = 80 mi
I'm not sure how common this is, but the speedometer in my car has
scales for both mph and km/h, so in principle I don't need to convert.
In practice, though, I have the above table in my head, from the old
days. It's easily remembered because the right-hand column corresponds
to the usual preferred values for UK speed limits.
Also, most modern cars can be persuaded to display speed (digitally) in
either mph or kph to suit your current needs.
Bertel Lund Hansen
2024-09-20 19:44:31 UTC
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Post by Sam Plusnet
Post by Phil
I'm not sure how common this is, but the speedometer in my car has
scales for both mph and km/h, so in principle I don't need to convert.
In practice, though, I have the above table in my head, from the old
days. It's easily remembered because the right-hand column corresponds
to the usual preferred values for UK speed limits.
Also, most modern cars can be persuaded to display speed (digitally) in
either mph or kph to suit your current needs.
Now that you mention it. I had completely forgotten, but I can change
the setup of mine to show miles. I dare not activate it, though. With my
failing memory I would get speeding tickets.
--
Bertel
Kolt, Denmark
Aidan Kehoe
2024-09-21 06:31:25 UTC
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[...] Also, most modern cars can be persuaded to display speed (digitally)
in either mph or kph to suit your current needs.
My then wife was using our car for her own reasons at one point in 2019 or so,
and living on the border I rented a Citroën in Northern Ireland since that was
the closest business that would do that for me. It was a UK model, and its
digital speedometer was in miles per hour with nothing in the manual to suggest
how to change that. So for four or five days I was doing the mental arithmetic
in the opposite direction from my norm. Not a big deal in the grand scheme of
things, but an annoyance.
--
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)
Hibou
2024-09-21 07:20:06 UTC
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Post by Sam Plusnet
Also, most modern cars can be persuaded to display speed (digitally) in
either mph or kph to suit your current needs.
Our recent hire cars have displayed the speed limit, as read from limit
signs via their cameras. It is often wrong, displaying a recent speed
limit, not the current one - unsurprisingly, since in France there are a
variety of signs that set the speed (a crossed-out place name, for
instance), the camera lens may be dirty, a lorry may mask a sign, and so on.

Apparently, the crazy EU has made this flawed system the basis for
mandatory speed limiters (and the crazy UK has followed suit). If you
run into someone stuck at 30 kph on a 130 kph autoroute, that's probably
the reason.

"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane" -
<https://www.parkers.co.uk/car-advice/speed-limiters-what-they-mean-for-you/>

God preserve us from government!
Bertel Lund Hansen
2024-09-21 07:45:02 UTC
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Post by Hibou
"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane"
My father has some friends who steadily run into that problem on the
road that they use every day.

When you say that the system is mandatory in EU, does that mean that we
are not allowed to disable it? I select speed according to my gps, and
that is 5 kph faster than the speedometer reading. It's pretty much been
the same with every car that I rented before I bought one.
--
Bertel
Kolt, Denmark
Hibou
2024-09-21 07:51:54 UTC
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Post by Bertel Lund Hansen
Post by Hibou
"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane"
My father has some friends who steadily run into that problem on the
road that they use every day.
When you say that the system is mandatory in EU, does that mean that we
are not allowed to disable it? I select speed according to my gps, and
that is 5 kph faster than the speedometer reading. It's pretty much been
the same with every car that I rented before I bought one.
Yes, car speedos are allowed to over-read but not under-read. GPS is
more accurate (except in tunnels).

It seems you can disable the speed limiter, but you have to do that
every time you start the car (and the maker may perhaps bury the option
several menus down).
Bertel Lund Hansen
2024-09-21 15:41:21 UTC
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Post by Hibou
Yes, car speedos are allowed to over-read but not under-read. GPS is
more accurate (except in tunnels).
It seems you can disable the speed limiter, but you have to do that
every time you start the car (and the maker may perhaps bury the option
several menus down).
A technical question that you may not be able to answer:

I always use cruise control. Will one in a a new car automatically
activate the sign reading limiter? If so, I'm screwed.
--
Bertel
Kolt, Denmark
Silvano
2024-09-21 10:52:12 UTC
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Post by Hibou
Post by Sam Plusnet
Also, most modern cars can be persuaded to display speed (digitally)
in either mph or kph to suit your current needs.
Our recent hire cars have displayed the speed limit, as read from limit
signs via their cameras. It is often wrong, displaying a recent speed
limit, not the current one - unsurprisingly, since in France there are a
variety of signs that set the speed (a crossed-out place name, for
instance), the camera lens may be dirty, a lorry may mask a sign, and so on.
Apparently, the crazy EU has made this flawed system the basis for
mandatory speed limiters (and the crazy UK has followed suit). If you
run into someone stuck at 30 kph on a 130 kph autoroute, that's probably
the reason.
"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane" -
<https://www.parkers.co.uk/car-advice/speed-limiters-what-they-mean-for-you/>
God preserve us from government!
Japan was already wiser 40 years ago, but the more appropriate name is
probably "speed limit warnings".
A friend gave me a ride there when an alarm sound went off.
- What does this noise mean?
- I was driving at over 100 km/h (the speed limit on their highways at
that time). We have a warning system on all our cars.
- What about all those cars overtaking us? Do they produce the same noise?
- Yes.
occam
2024-09-21 14:01:56 UTC
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Post by Silvano
Post by Hibou
Post by Sam Plusnet
Also, most modern cars can be persuaded to display speed (digitally)
in either mph or kph to suit your current needs.
Our recent hire cars have displayed the speed limit, as read from limit
signs via their cameras. It is often wrong, displaying a recent speed
limit, not the current one - unsurprisingly, since in France there are a
variety of signs that set the speed (a crossed-out place name, for
instance), the camera lens may be dirty, a lorry may mask a sign, and so on.
Apparently, the crazy EU has made this flawed system the basis for
mandatory speed limiters (and the crazy UK has followed suit). If you
run into someone stuck at 30 kph on a 130 kph autoroute, that's probably
the reason.
"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane" -
<https://www.parkers.co.uk/car-advice/speed-limiters-what-they-mean-for-you/>
God preserve us from government!
Japan was already wiser 40 years ago, but the more appropriate name is
probably "speed limit warnings".
A friend gave me a ride there when an alarm sound went off.
- What does this noise mean?
- I was driving at over 100 km/h (the speed limit on their highways at
that time). We have a warning system on all our cars.
- What about all those cars overtaking us? Do they produce the same noise?
- Yes.
This sound warning is optional on my car (i.e. can be disabled). The
visual warning (on the GPS display) however, is not. As soon as you go
over the speed limit, the colour of the limit indicator changes (to
red). The absence of a sound warning is a blessing, rather than a
handicap. It is annoying most of the time, and can be dangerous at other
times e.g. when you are accelerating for a good reason.
Aidan Kehoe
2024-09-21 15:10:37 UTC
Reply
Permalink
Post by occam
Post by Silvano
Post by Hibou
Post by Sam Plusnet
Also, most modern cars can be persuaded to display speed (digitally)
in either mph or kph to suit your current needs.
Our recent hire cars have displayed the speed limit, as read from limit
signs via their cameras. It is often wrong, displaying a recent speed
limit, not the current one - unsurprisingly, since in France there are a
variety of signs that set the speed (a crossed-out place name, for
instance), the camera lens may be dirty, a lorry may mask a sign, and so on.
Apparently, the crazy EU has made this flawed system the basis for
mandatory speed limiters (and the crazy UK has followed suit). If you
run into someone stuck at 30 kph on a 130 kph autoroute, that's probably
the reason.
A mandatory warning is part of the law, but actual restriction is not, so
should you be in those occasional situations where breaking the speed limit is
safer than following it, you can (usually, depending on your manufacturer) just
keep the foot on the accelerator despite the alarm.
Post by occam
Post by Silvano
Post by Hibou
"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane" -
<https://www.parkers.co.uk/car-advice/speed-limiters-what-they-mean-for-you/>
God preserve us from government!
Apart from things like seatbelt laws, high taxes on tobacco, enforced rules on
food safety, regulation of medication? Or are you completely fine with easily
avoidable death and major disability, shorter and worse-quality lives, mass
poisonings, more mass poisonings? The middle option saves on taxes given if you
die at 63 from lung cancer you won’t draw much in the way of state pension, so
there is a financial but not humanitarian argument for it. There’s no argument
for the rest.
Post by occam
Post by Silvano
Japan was already wiser 40 years ago, but the more appropriate name is
probably "speed limit warnings".
A friend gave me a ride there when an alarm sound went off.
- What does this noise mean?
- I was driving at over 100 km/h (the speed limit on their highways at
that time). We have a warning system on all our cars.
- What about all those cars overtaking us? Do they produce the same noise?
- Yes.
This sound warning is optional on my car (i.e. can be disabled). The
visual warning (on the GPS display) however, is not. As soon as you go
over the speed limit, the colour of the limit indicator changes (to
red). The absence of a sound warning is a blessing, rather than a
handicap. It is annoying most of the time, and can be dangerous at other
times e.g. when you are accelerating for a good reason.
--
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)
Silvano
2024-09-21 19:11:31 UTC
Reply
Permalink
Post by occam
Post by Silvano
Japan was already wiser 40 years ago, but the more appropriate name is
probably "speed limit warnings".
A friend gave me a ride there when an alarm sound went off.
- What does this noise mean?
- I was driving at over 100 km/h (the speed limit on their highways at
that time). We have a warning system on all our cars.
- What about all those cars overtaking us? Do they produce the same noise?
- Yes.
This sound warning is optional on my car (i.e. can be disabled). The
visual warning (on the GPS display) however, is not.
From what I saw at that time, Japan was ridiculously underdeveloped on
some items (washing machines, squat toilets - well, they moved on in
these 40 years and we should learn a lot from them about modern toilets,
see <https://en.wikipedia.org/wiki/Toilets_in_Japan>), but it was much
better than Continental Europe on other items (bullet trains, fax etc.).
But even they did not have GPS displays 40 years ago.


As soon as you go
Post by occam
over the speed limit, the colour of the limit indicator changes (to
red). The absence of a sound warning is a blessing, rather than a
handicap.
I agree, but you can't have a visual warning on the GPS display before
the invention of GPS displays. No idea about the present situation over
there.
Rich Ulrich
2024-09-22 01:28:29 UTC
Reply
Permalink
On Sat, 21 Sep 2024 21:11:31 +0200, Silvano
Post by Silvano
Post by occam
Post by Silvano
Japan was already wiser 40 years ago, but the more appropriate name is
probably "speed limit warnings".
A friend gave me a ride there when an alarm sound went off.
- What does this noise mean?
- I was driving at over 100 km/h (the speed limit on their highways at
that time). We have a warning system on all our cars.
- What about all those cars overtaking us? Do they produce the same noise?
- Yes.
This sound warning is optional on my car (i.e. can be disabled). The
visual warning (on the GPS display) however, is not.
From what I saw at that time, Japan was ridiculously underdeveloped on
some items (washing machines, squat toilets - well, they moved on in
these 40 years and we should learn a lot from them about modern toilets,
see <https://en.wikipedia.org/wiki/Toilets_in_Japan>), but it was much
better than Continental Europe on other items (bullet trains, fax etc.).
But even they did not have GPS displays 40 years ago.
I found that article on toilets in Japan to be interesting. I once
read a whole book about bathrooms, so it could be that I am easily
amused.

I learned that I can take one away ('toilets') from the set of things
never yet connected to the internet.
Post by Silvano
As soon as you go
Post by occam
over the speed limit, the colour of the limit indicator changes (to
red). The absence of a sound warning is a blessing, rather than a
handicap.
I agree, but you can't have a visual warning on the GPS display before
the invention of GPS displays. No idea about the present situation over
there.
--
Rich Ulrich
Janet
2024-09-22 12:29:47 UTC
Reply
Permalink
Post by Rich Ulrich
On Sat, 21 Sep 2024 21:11:31 +0200, Silvano
Post by Silvano
Post by occam
Post by Silvano
Japan was already wiser 40 years ago, but the more appropriate name is
probably "speed limit warnings".
A friend gave me a ride there when an alarm sound went off.
- What does this noise mean?
- I was driving at over 100 km/h (the speed limit on their highways at
that time). We have a warning system on all our cars.
- What about all those cars overtaking us? Do they produce the same noise?
- Yes.
This sound warning is optional on my car (i.e. can be disabled). The
visual warning (on the GPS display) however, is not.
From what I saw at that time, Japan was ridiculously underdeveloped on
some items (washing machines, squat toilets - well, they moved on in
these 40 years and we should learn a lot from them about modern toilets,
see <https://en.wikipedia.org/wiki/Toilets_in_Japan>), but it was much
better than Continental Europe on other items (bullet trains, fax etc.).
But even they did not have GPS displays 40 years ago.
I found that article on toilets in Japan to be interesting. I once
read a whole book about bathrooms, so it could be that I am easily
amused.
On my bucket-list; test-driving a Japanese-style
washlet toilet.

Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.

Janet
Bertel Lund Hansen
2024-09-22 14:52:37 UTC
Reply
Permalink
Post by Janet
On my bucket-list; test-driving a Japanese-style
washlet toilet.
Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
Don't forget the music that prevents toilet sounds to be heard.
--
Bertel
Kolt, Denmark
occam
2024-09-22 16:30:54 UTC
Reply
Permalink
Post by Janet
Post by Rich Ulrich
On Sat, 21 Sep 2024 21:11:31 +0200, Silvano
Post by Silvano
Post by occam
Post by Silvano
Japan was already wiser 40 years ago, but the more appropriate name is
probably "speed limit warnings".
A friend gave me a ride there when an alarm sound went off.
- What does this noise mean?
- I was driving at over 100 km/h (the speed limit on their highways at
that time). We have a warning system on all our cars.
- What about all those cars overtaking us? Do they produce the same noise?
- Yes.
This sound warning is optional on my car (i.e. can be disabled). The
visual warning (on the GPS display) however, is not.
From what I saw at that time, Japan was ridiculously underdeveloped on
some items (washing machines, squat toilets - well, they moved on in
these 40 years and we should learn a lot from them about modern toilets,
see <https://en.wikipedia.org/wiki/Toilets_in_Japan>), but it was much
better than Continental Europe on other items (bullet trains, fax etc.).
But even they did not have GPS displays 40 years ago.
I found that article on toilets in Japan to be interesting. I once
read a whole book about bathrooms, so it could be that I am easily
amused.
On my bucket-list; test-driving a Japanese-style
washlet toilet.
Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
Have you started learning Japanese for the voice activation part? One
wrong intonation, and the seat may incinerate your privates.
Silvano
2024-09-22 20:16:31 UTC
Reply
Permalink
Post by occam
Post by Janet
On my bucket-list; test-driving a Japanese-style
washlet toilet.
Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
Have you started learning Japanese for the voice activation part? One
wrong intonation, and the seat may incinerate your privates.
Just for your education, Japanese is NOT a tonal language. I do agree,
though, that you'd better learn the relevant ideograms before you use a
Japanese toilet, especially this one:
<Loading Image...>

Perhaps you're lucky and can use this one:
<Loading Image...>
I wonder what's the difference between shower and bidet here. Spray
height, as the picture suggests? I also wonder what you should do to
just flush your piss or poo.
Janet
2024-09-22 21:32:51 UTC
Reply
Permalink
Post by Silvano
Post by occam
Post by Janet
On my bucket-list; test-driving a Japanese-style
washlet toilet.
Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
Have you started learning Japanese for the voice activation part? One
wrong intonation, and the seat may incinerate your privates.
Just for your education, Japanese is NOT a tonal language. I do agree,
though, that you'd better learn the relevant ideograms before you use a
<https://en.wikipedia.org/wiki/Toilets_in_Japan#/media/File:Wireless_toilet_control_panel_w._open_lid.jpg>
<https://en.wikipedia.org/wiki/Toilets_in_Japan#/media/File:Modern_japanese_toilet.jpg>
I wonder what's the difference between shower and bidet here. Spray
height, as the picture suggests?
I would think , spray direction. Front or back.

Janet
lar3ryca
2024-09-23 05:08:48 UTC
Reply
Permalink
Post by occam
Post by Janet
Post by Rich Ulrich
On Sat, 21 Sep 2024 21:11:31 +0200, Silvano
Post by Silvano
Post by occam
Post by Silvano
Japan was already wiser 40 years ago, but the more appropriate name is
probably "speed limit warnings".
A friend gave me a ride there when an alarm sound went off.
- What does this noise mean?
- I was driving at over 100 km/h (the speed limit on their highways at
that time). We have a warning system on all our cars.
- What about all those cars overtaking us? Do they produce the same noise?
- Yes.
This sound warning is optional on my car (i.e. can be disabled). The
visual warning (on the GPS display) however, is not.
From what I saw at that time, Japan was ridiculously underdeveloped on
some items (washing machines, squat toilets - well, they moved on in
these 40 years and we should learn a lot from them about modern toilets,
see <https://en.wikipedia.org/wiki/Toilets_in_Japan>), but it was much
better than Continental Europe on other items (bullet trains, fax etc.).
But even they did not have GPS displays 40 years ago.
I found that article on toilets in Japan to be interesting. I once
read a whole book about bathrooms, so it could be that I am easily
amused.
On my bucket-list; test-driving a Japanese-style
washlet toilet.
Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
Have you started learning Japanese for the voice activation part? One
wrong intonation, and the seat may incinerate your privates.
Reminds me of an old joke, it ends with the doctor saying to his male
patient,
"You must have pressed the blue button! That activates the tampon remover!"
--
Doctor: "You have onomatopoeia"
"What is that?"
"It's exactly what it sounds like."
Bertel Lund Hansen
2024-09-23 05:47:16 UTC
Reply
Permalink
Post by lar3ryca
Reminds me of an old joke, it ends with the doctor saying to his male
patient,
"You must have pressed the blue button! That activates the tampon remover!"
It can't have been *that* old. How long have automatic toilets been
around?
--
Bertel
Kolt, Denmark
Peter Moylan
2024-09-23 07:23:44 UTC
Reply
Permalink
Post by Bertel Lund Hansen
Post by lar3ryca
Reminds me of an old joke, it ends with the doctor saying to his
male patient, "You must have pressed the blue button! That
activates the tampon remover!"
It can't have been *that* old. How long have automatic toilets been
around?
In the novel "Puckoon" (1963), by Skike Milligan, a castle owner had a
very special toilet built. It might have included a water squirter and a
hot air dryer, but I've forgotten that level of detail. What I do
remember is that, among its other features, it could be elevated and
then moved around. One the floor below were painted the portraits of a
number of traditional enemies of the family.
--
Peter Moylan ***@pmoylan.org http://www.pmoylan.org
Newcastle, NSW
Peter Moylan
2024-09-22 23:22:20 UTC
Reply
Permalink
Post by Janet
On my bucket-list; test-driving a Japanese-style
washlet toilet.
Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
I've just had a horrible thought. What if there are models that only
have cold water?
--
Peter Moylan ***@pmoylan.org http://www.pmoylan.org
Newcastle, NSW
Bertel Lund Hansen
2024-09-23 05:47:52 UTC
Reply
Permalink
Post by Peter Moylan
Post by Janet
On my bucket-list; test-driving a Japanese-style
washlet toilet.
Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
I've just had a horrible thought. What if there are models that only
have cold water?
You might just survive all the same.
--
Bertel
Kolt, Denmark
occam
2024-09-23 07:38:45 UTC
Reply
Permalink
Post by Peter Moylan
   On my bucket-list;  test-driving a Japanese-style
washlet toilet.
  Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
I've just had a horrible thought. What if there are models that only
have cold water?
What if there are models that have water (for squirting) and detergent -
for post-use cleaning of the seat? If the plumber gets the pipes the
wrong way around...
Janet
2024-09-23 12:19:53 UTC
Reply
Permalink
Post by Peter Moylan
Post by Janet
On my bucket-list; test-driving a Japanese-style
washlet toilet.
Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
I've just had a horrible thought. What if there are models that only
have cold water?
:-( a broken thermostat also risks a boiled bottom.

Janet
Sam Plusnet
2024-09-23 19:51:22 UTC
Reply
Permalink
Post by Peter Moylan
   On my bucket-list;  test-driving a Japanese-style
washlet toilet.
  Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
I've just had a horrible thought. What if there are models that only
have cold water?
Most hot water supplies run cold for quite some time before the water
finally warms up.
Snidely
2024-09-24 02:35:24 UTC
Reply
Permalink
On Monday or thereabouts, Sam Plusnet declared ...
   On my bucket-list;  test-driving a Japanese-style
washlet toilet.
  Must be the whole shebang with voice activated commands,
warm water bum wash and hot air dryer.
I've just had a horrible thought. What if there are models that only have
cold water?
Most hot water supplies run cold for quite some time before the water finally
warms up.
Depends on how far the heating element is from the orfice. Hence
instant-hot water taps. Or the hot water lines are looped.

/dps
--
"It wasn't just a splash in the pan"
-- lectricbikes.com
Hibou
2024-09-22 04:30:10 UTC
Reply
Permalink
Post by Aidan Kehoe
Post by Hibou
Our recent hire cars have displayed the speed limit, as read from limit
signs via their cameras. It is often wrong, displaying a recent speed
limit, not the current one - unsurprisingly, since in France there are a
variety of signs that set the speed (a crossed-out place name, for
instance), the camera lens may be dirty, a lorry may mask a sign, and so on.
Apparently, the crazy EU has made this flawed system the basis for
mandatory speed limiters (and the crazy UK has followed suit). If you
run into someone stuck at 30 kph on a 130 kph autoroute, that's probably
the reason.
A mandatory warning is part of the law, but actual restriction is not,
Do you have a source for that, a link?
Post by Aidan Kehoe
so
should you be in those occasional situations where breaking the speed limit is
safer than following it, you can (usually, depending on your manufacturer) just
keep the foot on the accelerator despite the alarm.
I think such situations are routine, not occasional.
Post by Aidan Kehoe
Post by Hibou
"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane" -
<https://www.parkers.co.uk/car-advice/speed-limiters-what-they-mean-for-you/>
God preserve us from government!
Apart from things like seatbelt laws, high taxes on tobacco, enforced rules on
food safety, regulation of medication? Or are you completely fine with easily
avoidable death and major disability, shorter and worse-quality lives, mass
poisonings, more mass poisonings? The middle option saves on taxes given if you
die at 63 from lung cancer you won’t draw much in the way of state pension, so
there is a financial but not humanitarian argument for it. There’s no argument
for the rest.
I think you've missed my point, which was that the system for
determining the speed limit is thoroughly unreliable, and not a suitable
basis for restrictors, or even alarms sounding in drivers' ears.


Let's explore a bit. To what extent should the state - or in the EU's
case the superstate - constrain people in order to make them safe?

A thought experiment. A parallel to inappropriate speed might be
inappropriate eating (I expect you know more about this than I).

"In the long-term, eating junk food can lead to: type 2 diabetes /
heart-related problems (such as cardiovascular disease, high blood
pressure and cholesterol) / overweight and obesity / osteoporosis /
certain cancers / depression /eating disorders / These complications are
all associated with a diet high in sugar, salt, trans- and saturated
fats and with a lack of essential nutrients like fibre, vitamins and
minerals" -
<https://www.healthdirect.gov.au/junk-food-and-your-health#complications>

Now, suppose it were possible to make an electronic implant that
monitored blood constituents, could detect when someone was digesting
junk food, and give that person a stomach ache.

Should the state force people to have that implant to save a proportion
of them from illness and premature death?

What if the implants' sensors were unreliable, and they often gave
people stomach aches even when they were eating healthily? Should the
state still make them mandatory?
Hibou
2024-09-22 04:36:28 UTC
Reply
Permalink
Post by Hibou
A thought experiment. A parallel to inappropriate speed might be
inappropriate eating (I expect you know more about this than I).
I mean you as a doctor, not as an eater.
Aidan Kehoe
2024-09-22 07:00:14 UTC
Reply
Permalink
Post by Hibou
Post by Hibou
A thought experiment. A parallel to inappropriate speed might be
inappropriate eating (I expect you know more about this than I).
I mean you as a doctor, not as an eater.
No offence taken!
--
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)
Aidan Kehoe
2024-09-22 06:59:33 UTC
Reply
Permalink
Post by Hibou
Post by Aidan Kehoe
Post by Hibou
Our recent hire cars have displayed the speed limit, as read from limit
signs via their cameras. It is often wrong, displaying a recent speed
limit, not the current one - unsurprisingly, since in France there are a
variety of signs that set the speed (a crossed-out place name, for
instance), the camera lens may be dirty, a lorry may mask a sign, and so on.
Apparently, the crazy EU has made this flawed system the basis for
mandatory speed limiters (and the crazy UK has followed suit). If you
run into someone stuck at 30 kph on a 130 kph autoroute, that's probably
the reason.
A mandatory warning is part of the law, but actual restriction is not,
Do you have a source for that, a link?
https://etsc.eu/intelligent-speed-assistance-isa/

“The European Union agreed in 2019 to make an overridable version of
[intelligent speed assistance], along with a number of other vehicle safety
measures, mandatory on new models of car sold in the EU from July 2022 and on
all new cars sold from July 2024.”
Post by Hibou
Post by Aidan Kehoe
so should you be in those occasional situations where breaking the speed
limit is safer than following it, you can (usually, depending on your
manufacturer) just keep the foot on the accelerator despite the alarm.
I think such situations are routine, not occasional.
Post by Aidan Kehoe
Post by Hibou
"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane" -
<https://www.parkers.co.uk/car-advice/speed-limiters-what-they-mean-for-you/>
God preserve us from government!
Apart from things like seatbelt laws, high taxes on tobacco, enforced
rules on food safety, regulation of medication? Or are you completely fine
with easily avoidable death and major disability, shorter and
worse-quality lives, mass poisonings, more mass poisonings? The middle
option saves on taxes given if you die at 63 from lung cancer you won’t
draw much in the way of state pension, so there is a financial but not
humanitarian argument for it. There’s no argument for the rest.
I think you've missed my point, which was that the system for determining
the speed limit is thoroughly unreliable, and not a suitable basis for
restrictors, or even alarms sounding in drivers' ears.
Ah, maybe I have. My 2019 Toyota Corolla has a system that reads the
speed-limit signs, displays the currently active speed limit, and changes the
usual black-numbers-on-a-white-background display to
white-numbers-on-a-red-background if I exceed that speed. It very occasionally
gets things wrong but is usually reliable, even on those parts of the island
afflicted by speed limits in MPH. So my reading of things is from my own
relevant experience rather than a journalist driving clicks.
Post by Hibou
Let's explore a bit. To what extent should the state - or in the EU's case
the superstate - constrain people in order to make them safe?
It depends on the size of the safety benefit vs the tightness of the
constraint, and reasonable people can differ on where to make that trade-off,
which is why e.g. different jurisdictions have different drink-driving
thresholds.

Something the EU definitely gets wrong is banning anabolic steroids given to
livestock raised for slaughter, something that has been standard in the US for
decades without demonstrated ill-effect.
Post by Hibou
A thought experiment. A parallel to inappropriate speed might be
inappropriate eating (I expect you know more about this than I).
"In the long-term, eating junk food can lead to: type 2 diabetes /
heart-related problems (such as cardiovascular disease, high blood pressure
and cholesterol) / overweight and obesity / osteoporosis / certain cancers /
depression /eating disorders / These complications are all associated with a
diet high in sugar, salt, trans- and saturated fats and with a lack of
essential nutrients like fibre, vitamins and minerals" -
<https://www.healthdirect.gov.au/junk-food-and-your-health#complications>
Now, suppose it were possible to make an electronic implant that monitored
blood constituents, could detect when someone was digesting junk food, and
give that person a stomach ache.
Should the state force people to have that implant to save a proportion of
them from illness and premature death?
The state almost certainly shouldn’t be spending the money to implant this in
everyone, I’d rule it out for that reason. But on pure medical grounds, no,
people have a right to bodily autonomy, it is unethical to make such a thing
mandatory. If a life insurance company were to offer reduced premiums to people
willing to have such a sensor, that would be fine.
Post by Hibou
What if the implants' sensors were unreliable, and they often gave people
stomach aches even when they were eating healthily? Should the state still
make them mandatory?
--
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)
Peter Moylan
2024-09-22 08:13:28 UTC
Reply
Permalink
Post by Aidan Kehoe
Post by Hibou
I think you've missed my point, which was that the system for
determining the speed limit is thoroughly unreliable, and not a
suitable basis for restrictors, or even alarms sounding in drivers'
ears.
Ah, maybe I have. My 2019 Toyota Corolla has a system that reads the
speed-limit signs, displays the currently active speed limit, and
changes the usual black-numbers-on-a-white-background display to
white-numbers-on-a-red-background if I exceed that speed. It very
occasionally gets things wrong but is usually reliable, even on those
parts of the island afflicted by speed limits in MPH. So my reading
of things is from my own relevant experience rather than a journalist
driving clicks.
My car, which is 14 years old, doesn't have such a feature. Despite that
my GPS navigator manages to display the speed limit, except in places
where reception from satellites is blocked. I assume that the limits are
contained in map data. Why then would the car need to read roadside signs?

OK, I'll concede that there are sometimes temporary limits in place
because of roadworks and so on, but that's the exceptional case.
--
Peter Moylan ***@pmoylan.org http://www.pmoylan.org
Newcastle, NSW
Snidely
2024-09-22 08:49:39 UTC
Reply
Permalink
Post by Peter Moylan
Post by Aidan Kehoe
Post by Hibou
I think you've missed my point, which was that the system for
determining the speed limit is thoroughly unreliable, and not a
suitable basis for restrictors, or even alarms sounding in drivers'
ears.
Ah, maybe I have. My 2019 Toyota Corolla has a system that reads the
speed-limit signs, displays the currently active speed limit, and
changes the usual black-numbers-on-a-white-background display to
white-numbers-on-a-red-background if I exceed that speed. It very
occasionally gets things wrong but is usually reliable, even on those
parts of the island afflicted by speed limits in MPH. So my reading
of things is from my own relevant experience rather than a journalist
driving clicks.
My car, which is 14 years old, doesn't have such a feature. Despite that
my GPS navigator manages to display the speed limit, except in places
where reception from satellites is blocked. I assume that the limits are
contained in map data. Why then would the car need to read roadside signs?
Map data is often incomplete. I've had examples where my car has
displayed the wrong speed limit from map data, and then corrects it
when I manage to find a sign.

I've experienced very few errors with my car, the main examples being
school speed limits which are, per California law as related by the
driver's manual, only applicable when children are present on the
sidewalks and in the crosswalks around the school.
Post by Peter Moylan
OK, I'll concede that there are sometimes temporary limits in place
because of roadworks and so on, but that's the exceptional case.
Not at all exceptional in California on the freeways, although the
location changes from time to time.

/dps
--
Trust, but verify.
Aidan Kehoe
2024-09-22 09:16:51 UTC
Reply
Permalink
Post by Peter Moylan
Post by Aidan Kehoe
Post by Hibou
I think you've missed my point, which was that the system for
determining the speed limit is thoroughly unreliable, and not a
suitable basis for restrictors, or even alarms sounding in drivers'
ears.
Ah, maybe I have. My 2019 Toyota Corolla has a system that reads the
speed-limit signs, displays the currently active speed limit, and
changes the usual black-numbers-on-a-white-background display to
white-numbers-on-a-red-background if I exceed that speed. It very
occasionally gets things wrong but is usually reliable, even on those
parts of the island afflicted by speed limits in MPH. So my reading
of things is from my own relevant experience rather than a journalist
driving clicks.
My car, which is 14 years old, doesn't have such a feature. Despite that
my GPS navigator manages to display the speed limit, except in places
where reception from satellites is blocked. I assume that the limits are
contained in map data. Why then would the car need to read roadside signs?
I was working on the assumption that the car does not have a GPS receiver; it
has a SIM card and will call the emergency services if it feels there is an
accident, and my working understanding was that its location sensing was done
in the same way that mobile phones do, with triangulation from masts.

However I have no mobile reception where I live and when I check today it does
seem to work out the location with reasonable fidelity (I don’t normallly use
the built-in navigation, Toyota do not excel at software) so it may have a
built-in GPS.
Post by Peter Moylan
OK, I'll concede that there are sometimes temporary limits in place
because of roadworks and so on, but that's the exceptional case.
It does pick up temporary speed limit signs that are unlikely to be in the map
data.
--
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)
Aidan Kehoe
2024-10-03 07:38:20 UTC
Reply
Permalink
Post by Aidan Kehoe
I was working on the assumption that the car does not have a GPS receiver;
it has a SIM card and will call the emergency services if it feels there is
an accident, and my working understanding was that its location sensing was
done in the same way that mobile phones do, with triangulation from masts.
However I have no mobile reception where I live and when I check today it
does seem to work out the location with reasonable fidelity (I don’t
normallly use the built-in navigation, Toyota do not excel at software) so
it may have a built-in GPS.
Yesterday morning was relatively cold and cloudy and on turning on the car the
navigation suggested that the car was in the ocean and that the speed limits
were unknown. This did not change on driving to an area with phone reception.
It has corrected itself today. So, the location sensing is almost certainly
from a GPS receiver rather than its SIM card.
--
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)
Bertel Lund Hansen
2024-09-22 09:33:02 UTC
Reply
Permalink
Post by Peter Moylan
My car, which is 14 years old, doesn't have such a feature. Despite that
my GPS navigator manages to display the speed limit, except in places
where reception from satellites is blocked. I assume that the limits are
contained in map data. Why then would the car need to read roadside signs?
OK, I'll concede that there are sometimes temporary limits in place
because of roadworks and so on, but that's the exceptional case.
It's not exceptional in Denmark. P.t. there are major repairs and
expansions on the motorways in Jutland. The won't be finished till 2026.

Okay, that's not everyday life, But I regularly see temporary speed
around road work.

Google Maps, which I use, is updated by user input and statistics, so it
takes some time until it gets it right.

Aside: GM has impressed me a couple of times. It gave me a route which
led to a road closed by road workers. A naive navigation would have
insisted on the same route, but when I turned the car around, GM gave me
another route that was open.
--
Bertel
Kolt, Denmark
Bertel Lund Hansen
2024-09-22 09:27:27 UTC
Reply
Permalink
Post by Aidan Kehoe
Post by Hibou
Should the state force people to have that implant to save a proportion of
them from illness and premature death?
The state almost certainly shouldn’t be spending the money to implant this in
everyone, I’d rule it out for that reason. But on pure medical grounds, no,
people have a right to bodily autonomy, it is unethical to make such a thing
mandatory. If a life insurance company were to offer reduced premiums to people
willing to have such a sensor, that would be fine.
The comma after "no" is quite important. I missed it in my first reading
and got confused when I got to the text after the next comma.

My insurance company has given me the option to let them monitor my
driving which I accepted. If I drive carefully, the premium will be
reduced. I score 8 out of ten with my normal driving.
--
Bertel
Kolt, Denmark
Janet
2024-09-22 12:36:03 UTC
Reply
Permalink
Post by Bertel Lund Hansen
Post by Hibou
Should the state force people to have that implant to save a proportion of
them from illness and premature death?
The state almost certainly shouldn?t be spending the money to implant this in
everyone, I?d rule it out for that reason. But on pure medical grounds, no,
people have a right to bodily autonomy, it is unethical to make such a thing
mandatory. If a life insurance company were to offer reduced premiums to people
willing to have such a sensor, that would be fine.
The comma after "no" is quite important. I missed it in my first reading
and got confused when I got to the text after the next comma.
My insurance company has given me the option to let them monitor my
driving which I accepted. If I drive carefully, the premium will be
reduced. I score 8 out of ten with my normal driving.
Excellent idea; one day all car insurers will work like
that.

Janet
Sam Plusnet
2024-09-22 20:59:40 UTC
Reply
Permalink
Post by Aidan Kehoe
Post by Hibou
Post by Aidan Kehoe
Post by Hibou
Our recent hire cars have displayed the speed limit, as read from limit
signs via their cameras. It is often wrong, displaying a recent speed
limit, not the current one - unsurprisingly, since in France there are a
variety of signs that set the speed (a crossed-out place name, for
instance), the camera lens may be dirty, a lorry may mask a sign, and so
on.
Apparently, the crazy EU has made this flawed system the basis for
mandatory speed limiters (and the crazy UK has followed suit). If you
run into someone stuck at 30 kph on a 130 kph autoroute, that's probably
the reason.
A mandatory warning is part of the law, but actual restriction is not,
Do you have a source for that, a link?
https://etsc.eu/intelligent-speed-assistance-isa/
“The European Union agreed in 2019 to make an overridable version of
[intelligent speed assistance], along with a number of other vehicle safety
measures, mandatory on new models of car sold in the EU from July 2022 and on
all new cars sold from July 2024.”
Post by Hibou
Post by Aidan Kehoe
so should you be in those occasional situations where breaking the speed
limit is safer than following it, you can (usually, depending on your
manufacturer) just keep the foot on the accelerator despite the alarm.
I think such situations are routine, not occasional.
Post by Aidan Kehoe
Post by Hibou
"However, our experience of such systems suggests they can get it wrong.
In one instance, a car's traffic sign recognition system picked up a
30mph sign on a turning off a dual carriage and dramatically slowed
down, despite the fact the car was actually travelling along the outside
lane" -
<https://www.parkers.co.uk/car-advice/speed-limiters-what-they-mean-for-you/>
God preserve us from government!
Apart from things like seatbelt laws, high taxes on tobacco, enforced
rules on food safety, regulation of medication? Or are you completely fine
with easily avoidable death and major disability, shorter and
worse-quality lives, mass poisonings, more mass poisonings? The middle
option saves on taxes given if you die at 63 from lung cancer you won’t
draw much in the way of state pension, so there is a financial but not
humanitarian argument for it. There’s no argument for the rest.
I think you've missed my point, which was that the system for determining
the speed limit is thoroughly unreliable, and not a suitable basis for
restrictors, or even alarms sounding in drivers' ears.
Ah, maybe I have. My 2019 Toyota Corolla has a system that reads the
speed-limit signs, displays the currently active speed limit, and changes the
usual black-numbers-on-a-white-background display to
white-numbers-on-a-red-background if I exceed that speed. It very occasionally
gets things wrong but is usually reliable, even on those parts of the island
afflicted by speed limits in MPH. So my reading of things is from my own
relevant experience rather than a journalist driving clicks.
This will be more of a problem for some, depending upon where you live.

My car uses a combination of satnav map data which includes the set
speed limit on each road, plus the output of the camera which (attempts
to) read speed limit signs.

Since the default speed limit in Wales was reduced to 20mph, the speed
limit displayed by my car has been wrong more often than it is
correct[1] - and not just reading "30" when it ought to be "20".

At the moment that is a nuisance.
If that same incorrect data is to be used in the way described in this
thread, it becomes far more than a nuisance.

[1] In a 8 mile radius around my home, I am not exaggerating when I say
"more often wrong that correct". - and yes the satnav's mapping data has
been updated twice in the year since the limit was changed.
Aidan Kehoe
2024-09-22 21:18:13 UTC
Reply
Permalink
Post by Sam Plusnet
Post by Aidan Kehoe
Ah, maybe I have. My 2019 Toyota Corolla has a system that reads the
speed-limit signs, displays the currently active speed limit, and changes
the usual black-numbers-on-a-white-background display to
white-numbers-on-a-red-background if I exceed that speed. It very
occasionally gets things wrong but is usually reliable, even on those
parts of the island afflicted by speed limits in MPH. So my reading of
things is from my own relevant experience rather than a journalist driving
clicks.
This will be more of a problem for some, depending upon where you live.
My car uses a combination of satnav map data which includes the set speed
limit on each road, plus the output of the camera which (attempts to) read
speed limit signs.
Since the default speed limit in Wales was reduced to 20mph, the speed limit
displayed by my car has been wrong more often than it is correct[1] - and not
just reading "30" when it ought to be "20".
That is very tedious, and a very different situation to mine.
Post by Sam Plusnet
At the moment that is a nuisance. If that same incorrect data is to be used
in the way described in this thread, it becomes far more than a nuisance.
No rush to buy a new car, then.
Post by Sam Plusnet
[1] In a 8 mile radius around my home, I am not exaggerating when I say
"more often wrong that correct". - and yes the satnav's mapping data has
been updated twice in the year since the limit was changed.
--
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)
Sam Plusnet
2024-09-23 19:57:16 UTC
Reply
Permalink
Post by Aidan Kehoe
Post by Sam Plusnet
Post by Aidan Kehoe
Ah, maybe I have. My 2019 Toyota Corolla has a system that reads the
speed-limit signs, displays the currently active speed limit, and changes
the usual black-numbers-on-a-white-background display to
white-numbers-on-a-red-background if I exceed that speed. It very
occasionally gets things wrong but is usually reliable, even on those
parts of the island afflicted by speed limits in MPH. So my reading of
things is from my own relevant experience rather than a journalist driving
clicks.
This will be more of a problem for some, depending upon where you live.
My car uses a combination of satnav map data which includes the set speed
limit on each road, plus the output of the camera which (attempts to) read
speed limit signs.
Since the default speed limit in Wales was reduced to 20mph, the speed limit
displayed by my car has been wrong more often than it is correct[1] - and not
just reading "30" when it ought to be "20".
That is very tedious, and a very different situation to mine.
Post by Sam Plusnet
At the moment that is a nuisance. If that same incorrect data is to be used
in the way described in this thread, it becomes far more than a nuisance.
No rush to buy a new car, then.
No, but the car's maker publishes software updates a couple of times per
year.
Since my elderly car has all the attributes needed to operate the new
legally required changes, it seems quite likely that they may be
included in one of those updates - without fair warning (they don't give
much information about what is (or isn't) in an update.
Post by Aidan Kehoe
Post by Sam Plusnet
[1] In a 8 mile radius around my home, I am not exaggerating when I say
"more often wrong that correct". - and yes the satnav's mapping data has
been updated twice in the year since the limit was changed.
Phil
2024-09-21 14:30:14 UTC
Reply
Permalink
Post by Sam Plusnet
Post by Phil
Post by Bertel Lund Hansen
Post by Helmut Richter
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I haven't neede it, but just for fun I have calculated the Danish speed
         50 km = 30 mi
         80 km = 50 mi
       110 km = 70 mi (2 km too much)
       130 km = 80 mi
I'm not sure how common this is, but the speedometer in my car has
scales for both mph and km/h, so in principle I don't need to convert.
In practice, though, I have the above table in my head, from the old
days. It's easily remembered because the right-hand column corresponds
to the usual preferred values for UK speed limits.
Also, most modern cars can be persuaded to display speed (digitally) in
either mph or kph to suit your current needs.
Ah yes, I was forgetting just how old-school my car is -- it has an
actual needle moving on a circular scale.
--
Phil B
Bertel Lund Hansen
2024-09-21 15:44:57 UTC
Reply
Permalink
Post by Phil
Ah yes, I was forgetting just how old-school my car is -- it has an
actual needle moving on a circular scale.
You mean "physical". My car has a virtual, oldfashioned speedometer, but
I always use the digital one. It's much nicer when I set the speed
limit.
--
Bertel
Kolt, Denmark
lar3ryca
2024-09-23 04:58:06 UTC
Reply
Permalink
Post by Bertel Lund Hansen
Post by Helmut Richter
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.

I do pretty much mental conversions for distance, volume, weight, but I
have no use at all for metric area or pressure (to name just 2).
Almost nobody in these parts would speak to me in those terms, nor would
they know what magnitude I was speaking of.
--
I took a course in speed waiting.
Now I can wait an hour in only ten minutes.
Bertel Lund Hansen
2024-09-23 05:50:03 UTC
Reply
Permalink
Post by lar3ryca
Post by Bertel Lund Hansen
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
--
Bertel
Kolt, Denmark
Peter Moylan
2024-09-23 07:25:09 UTC
Reply
Permalink
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
And the analogue of mph is km/h.
--
Peter Moylan ***@pmoylan.org http://www.pmoylan.org
Newcastle, NSW
lar3ryca
2024-09-23 22:03:09 UTC
Reply
Permalink
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
Definitely not. A kilometre is not a speed, and a mile is not a speed.

There's a newsreader on a local radio station that insists on reporting
wind speeds as 'nn kilometres'.
It's a wonder I have any teeth left, after grinding them most mornings.
--
Soy milk is just regular milk, introducing itself in Spanish.
Kerr-Mudd, John
2024-09-24 09:28:09 UTC
Reply
Permalink
On Mon, 23 Sep 2024 16:03:09 -0600
Post by lar3ryca
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
Definitely not. A kilometre is not a speed, and a mile is not a speed.
There's a newsreader on a local radio station that insists on reporting
wind speeds as 'nn kilometres'.
It's a wonder I have any teeth left, after grinding them most mornings.
Our local traffic report readers seem to have difficulty telling us that
'X road is closed *due* to an accident'. They skip the 'due' word.
More teeth shortening stuff.
--
Bah, and indeed Humbug.
J. J. Lodder
2024-09-24 09:28:15 UTC
Reply
Permalink
Post by lar3ryca
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
Definitely not. A kilometre is not a speed, and a mile is not a speed.
There's a newsreader on a local radio station that insists on reporting
wind speeds as 'nn kilometres'.
It's a wonder I have any teeth left, after grinding them most mornings.
It's unlikely to be kilometers per second...

Jan
lar3ryca
2024-09-25 05:45:10 UTC
Reply
Permalink
Post by J. J. Lodder
Post by lar3ryca
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
Definitely not. A kilometre is not a speed, and a mile is not a speed.
There's a newsreader on a local radio station that insists on reporting
wind speeds as 'nn kilometres'.
It's a wonder I have any teeth left, after grinding them most mornings.
It's unlikely to be kilometers per second...
Not the point. A newsreader is paid to speak. The least s/he/it can do
is speak properly.
--
Damn these human beings; if I had invented them I would go hide my head
in a bag.
–Mark Twain
Bertel Lund Hansen
2024-09-25 08:37:42 UTC
Reply
Permalink
Post by lar3ryca
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
Definitely not. A kilometre is not a speed, and a mile is not a speed.
Really? What a surprise.

I haven't said that they were. I showed conversion between two length
units. The intelligent reader would then immediately know that the same
conversion can be use by speeds.
--
Bertel
Kolt, Denmark
charles
2024-09-25 09:00:02 UTC
Reply
Permalink
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
Definitely not. A kilometre is not a speed, and a mile is not a speed.
Really? What a surprise.
I haven't said that they were. I showed conversion between two length
units. The intelligent reader would then immediately know that the same
conversion can be use by speeds.
at least both measurement systems us the same time units.
--
from KT24 in Surrey, England - sent from my RISC OS 4té²
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
J. J. Lodder
2024-09-25 20:46:41 UTC
Reply
Permalink
Post by charles
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
Post by lar3ryca
Post by Bertel Lund Hansen
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
'mi' should be 'MPH'.
No. km ~ mi
Definitely not. A kilometre is not a speed, and a mile is not a speed.
Really? What a surprise.
I haven't said that they were. I showed conversion between two length
units. The intelligent reader would then immediately know that the same
conversion can be use by speeds.
at least both measurement systems us the same time units.
Unfortunately, yes.
It would have been much better if the decimal seconds
had been succesfully introduced.

Jan
--
BTW, the weatherman in these parts uses 'Beaufort',
pronounced as if the admiral had been a Frenchman.
'Everyone' knows that storms begin at Beaufort seven,
few know with how many m/s or km/h that corresponds.
Phil
2024-09-25 13:40:44 UTC
Reply
Permalink
Post by Bertel Lund Hansen
Post by Helmut Richter
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
I was more than a little surprised, just this morning, to find that in
my local branch of Halfords, for a mere £3.99, I can buy a handy guide
to stick on my windscreen:

<https://www.halfords.com/motoring/travel-accessories/travel-equipment/speedright-safety-device-181812.html?stockInventory=undefined>

I can't help wondering who, in the 21st century, is expected to buy this
"safety device".
--
Phil B
Kerr-Mudd, John
2024-09-26 09:40:15 UTC
Reply
Permalink
On Wed, 25 Sep 2024 14:40:44 +0100
Post by Phil
Post by Bertel Lund Hansen
Post by Helmut Richter
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I haven't neede it, but just for fun I have calculated the Danish speed
50 km = 30 mi
80 km = 50 mi
110 km = 70 mi (2 km too much)
130 km = 80 mi
I was more than a little surprised, just this morning, to find that in
my local branch of Halfords, for a mere £3.99, I can buy a handy guide
<https://www.halfords.com/motoring/travel-accessories/travel-equipment/speedright-safety-device-181812.html?stockInventory=undefined>
I can't help wondering who, in the 21st century, is expected to buy this
"safety device".
Classic cars without dual display?
But requiring scriptytosh to view the website is standard.
--
Bah, and indeed Humbug.
Bertel Lund Hansen
2024-09-26 13:55:22 UTC
Reply
Permalink
Post by Kerr-Mudd, John
Post by Phil
I was more than a little surprised, just this morning, to find that in
my local branch of Halfords, for a mere £3.99, I can buy a handy guide
<https://www.halfords.com/motoring/travel-accessories/travel-equipment/speedright-safety-device-181812.html?stockInventory=undefined>
I can't help wondering who, in the 21st century, is expected to buy this
"safety device".
Classic cars without dual display?
I see in my mind a driver who smashes into an oncoming vehicle while
studying the table.
--
Bertel
Kolt, Denmark
Snidely
2024-09-26 23:47:27 UTC
Reply
Permalink
Post by Bertel Lund Hansen
Post by Kerr-Mudd, John
Post by Phil
I was more than a little surprised, just this morning, to find that in
my local branch of Halfords, for a mere £3.99, I can buy a handy guide
<https://www.halfords.com/motoring/travel-accessories/travel-equipment/speedright-safety-device-181812.html?stockInventory=undefined>
I can't help wondering who, in the 21st century, is expected to buy this
"safety device".
Classic cars without dual display?
I see in my mind a driver who smashes into an oncoming vehicle while
studying the table.
Just paste it on the GPS display, so they don't run into a car while
trying to read the directions.

/dps
--
"It wasn't just a splash in the pan"
-- lectricbikes.com
Peter Moylan
2024-09-20 10:55:41 UTC
Reply
Permalink
Post by Helmut Richter
I like much more those thumb rules that actually allow you to estimate orders
1 year ≅ π · 10⁷ sec ≅ 31415926.54 sec
or
1 year ≅ √10 · 10⁷ sec ≅ 31622776.60 sec
or, only for those wanting more precision, the arithmetic mean of the two
which has three leading digits correct.
The one non-metric measurement that I find useful is "one foot per
nanosecond".
--
Peter Moylan ***@pmoylan.org http://www.pmoylan.org
Newcastle, NSW
J. J. Lodder
2024-09-22 15:50:00 UTC
Reply
Permalink
Post by Peter Moylan
Post by Helmut Richter
I like much more those thumb rules that actually allow you to estimate
1 year ? π · 10? sec ? 31415926.54 sec
or
1 year ? √10 · 10? sec ? 31622776.60 sec
or, only for those wanting more precision, the arithmetic mean of the two
which has three leading digits correct.
The one non-metric measurement that I find useful is "one foot per
nanosecond".
Impossible to go that fast,

Jan
Peter Moylan
2024-09-22 23:32:24 UTC
Reply
Permalink
Post by J. J. Lodder
Post by Peter Moylan
The one non-metric measurement that I find useful is "one foot per
nanosecond".
Impossible to go that fast,
Useful, though, to get an estimate of the time delays across the width
of a printed circuit board.

I'm not actually involved in high-speed electronics, but I think the
current rule of thumb is that the speed of signals on a printed circuit
board is about two-thirds of the speed in a vacuum.
--
Peter Moylan ***@pmoylan.org http://www.pmoylan.org
Newcastle, NSW
J. J. Lodder
2024-09-28 21:29:25 UTC
Reply
Permalink
Post by Peter Moylan
Post by J. J. Lodder
Post by Peter Moylan
The one non-metric measurement that I find useful is "one foot per
nanosecond".
Impossible to go that fast,
Useful, though, to get an estimate of the time delays across the width
of a printed circuit board.
I'm not actually involved in high-speed electronics, but I think the
current rule of thumb is that the speed of signals on a printed circuit
board is about two-thirds of the speed in a vacuum.
Metric still beats you: 30 cm/nanosecond is more accurate.
BTW, just to annoy the dimension fundies, (if any)
it is nowadays quite correct to say that a nanosecond equals a foot,
(or 30 cm) almost,

Jan
J. J. Lodder
2024-09-20 20:24:26 UTC
Reply
Permalink
Post by Helmut Richter
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
... the English-speaking world with the exception of Ireland, Canada,
Australia, New Zealand, and South Africa and some others.
I think the term "United Kingdom and USA" would have been shorter and
slightly more accurate.
Post by Christian Weisgerber
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
And easier to remember than 1.609344. But when will you need such precision?
For instance, when you drive on German roads outside villages, you must
reduce your speed to 31.0685 mph whereas the rough rule 1 mi = 1.6 km would
have allowed you 31.2500 mph.
I like much more those thumb rules that actually allow you to estimate orders
1 year ? π · 10? sec ? 31415926.54 sec
or
1 year ? √10 · 10? sec ? 31622776.60 sec
or, only for those wanting more precision, the arithmetic mean of the two
which has three leading digits correct.
For orders of magitude there are 10^5 seconds to a day,
and 400 days to a year, so 40 million seconds to a year.
Both numbers are rounded up,
so the actual number is about 30 million seconds to a year.
All quite memorable.
The correct answer is 31 557 600 seconds/year (exactly)
so a quite acceptable estimate,

Jan
charles
2024-09-21 08:30:02 UTC
Reply
Permalink
Post by Helmut Richter
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict the
English-speaking world.
... the English-speaking world with the exception of Ireland, Canada,
Australia, New Zealand, and South Africa and some others.
I think the term "United Kingdom and USA" would have been shorter and
slightly more accurate.
Post by Christian Weisgerber
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits. If nothing else, it's
faster to type on a calculator.
And easier to remember than 1.609344. But when will you need such
precision? For instance, when you drive on German roads outside
villages, you must reduce your speed to 31.0685 mph whereas the rough
rule 1 mi = 1.6 km would have allowed you 31.2500 mph.
I like much more those thumb rules that actually allow you to estimate
1 year ? ð · 10? sec ? 31415926.54 sec
or
1 year ? #10 · 10? sec ? 31622776.60 sec
or, only for those wanting more precision, the arithmetic mean of the
two which has three leading digits correct.
For orders of magitude there are 10^5 seconds to a day, and 400 days to a
year, so 40 million seconds to a year. Both numbers are rounded up, so
the actual number is about 30 million seconds to a year. All quite
memorable. The correct answer is 31 557 600 seconds/year (exactly) so a
quite acceptable estimate,
I remember being told that a second is about a "micro-fortnight". Not very
accurate, but the right order of magnitude.
--
from KT24 in Surrey, England - sent from my RISC OS 4té²
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
Christian Weisgerber
2024-09-20 20:11:33 UTC
Reply
Permalink
Post by Helmut Richter
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
... the English-speaking world with the exception of Ireland, Canada,
Australia, New Zealand, and South Africa and some others.
I'm well aware, but they still suffer exposure by way of American
media.

The American-Canadian border in particular is very leaky in this
regard. Canada is notionally fully metric, but economically aligned
with the US, and in practice you can find American units even in
Canadian French.
--
Christian "naddy" Weisgerber ***@mips.inka.de
J. J. Lodder
2024-09-23 07:58:05 UTC
Reply
Permalink
Post by Christian Weisgerber
Post by Helmut Richter
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
... the English-speaking world with the exception of Ireland, Canada,
Australia, New Zealand, and South Africa and some others.
I'm well aware, but they still suffer exposure by way of American
media.
The American-Canadian border in particular is very leaky in this
regard. Canada is notionally fully metric, but economically aligned
with the US, and in practice you can find American units even in
Canadian French.
The same applied originally.
Jefferson was a great fan of the metric system,
having discussed it a lot while in Paris,
but there was no way of pushing that through.
For all its proud independence the young republic
was still economically a colony,
depending for most of its manufactured stuff on England.
(so no way they could have their own units)

The only thing they got right from the start was their decimal currency,

Jan
jerryfriedman
2024-09-20 13:50:20 UTC
Reply
Permalink
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
Hey, that's closer than the golden ratio.

I only know log(5) = about 1.6 because my graduate adviser
suggested I learn log(2) = 0.7, log(3) = 1.1, log(7) = 2, and
log(20) = 3. It was handy for what I was doing.

--
Jerry Friedman
kami
2024-09-22 08:15:25 UTC
Reply
Permalink
On Thu, 19 Sep 2024 23:12:52 -0000 (UTC), Christian Weisgerber
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
simplest method is to multiply by 0.6
Snidely
2024-09-22 08:52:33 UTC
Reply
Permalink
Post by kami
On Thu, 19 Sep 2024 23:12:52 -0000 (UTC), Christian Weisgerber
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
simplest method is to multiply by 0.6
There's no humor in that.

-d
--
"I'm glad unicorns don't ever need upgrades."
"We are as up as it is possible to get graded!"
_Phoebe and Her Unicorn_, 2016.05.15
kami
2024-09-22 09:28:47 UTC
Reply
Permalink
Post by Snidely
Post by kami
On Thu, 19 Sep 2024 23:12:52 -0000 (UTC), Christian Weisgerber
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
simplest method is to multiply by 0.6
There's no humor in that.
-d
an easier method would be, if the limit is 80 miles per hour,
simply add half, which is 40 and then one tenth of that, which is
4 and multiply it by 2 which is 8, so 48 + 80 is 128 km/h

similarly lets say 120 miles per hour, half 60, tenth times 2 is
12, so 72 + 120 = 192 km/h.
Snidely
2024-09-22 10:19:42 UTC
Reply
Permalink
On Sunday, kami pointed out that ...
Post by kami
Post by Snidely
Post by kami
On Thu, 19 Sep 2024 23:12:52 -0000 (UTC), Christian Weisgerber
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
simplest method is to multiply by 0.6
There's no humor in that.
-d
an easier method would be, if the limit is 80 miles per hour,
simply add half, which is 40 and then one tenth of that, which is
4 and multiply it by 2 which is 8, so 48 + 80 is 128 km/h
similarly lets say 120 miles per hour, half 60, tenth times 2 is
12, so 72 + 120 = 192 km/h.
There's no humor in that.

-d
--
"It wasn't just a splash in the pan"
-- lectricbikes.com
Kerr-Mudd, John
2024-09-22 10:57:29 UTC
Reply
Permalink
On Sun, 22 Sep 2024 03:19:42 -0700
Post by Snidely
On Sunday, kami pointed out that ...
Post by kami
Post by Snidely
Post by kami
On Thu, 19 Sep 2024 23:12:52 -0000 (UTC), Christian Weisgerber
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
simplest method is to multiply by 0.6
There's no humor in that.
-d
an easier method would be, if the limit is 80 miles per hour,
simply add half, which is 40 and then one tenth of that, which is
4 and multiply it by 2 which is 8, so 48 + 80 is 128 km/h
similarly lets say 120 miles per hour, half 60, tenth times 2 is
12, so 72 + 120 = 192 km/h.
Sounds illegal to me.

70mph is the max in the UK, but only on motorways and dual carriageways (as
we so quaintly call them) - this means that the traffic in opposite
directions has a barrier between it, not as some naively think, that the
road has 2 or more lanes in the same direction).

A supermarket car park near me has 5mph signs; I've never seen any vehicle
travel that slow, unless manoeuvring into a slot.
Post by Snidely
There's no humor in that.
isn't there? if 0.6 is right then pshurely you want to add a half and a
tenth.

Or memorise a table:
(80) 130
(75) 120
70+35+7=112(110)
60+30+6= 96(100)
(55) 90
50+25+5= 80 80
(45) 70
40+20+4= 64 (60)
(35) 50
30+15+3= 38 (40)
20+10+2= 32 (30)
--
Bah, and indeed Humbug.
Bertel Lund Hansen
2024-09-22 14:58:58 UTC
Reply
Permalink
Post by Kerr-Mudd, John
A supermarket car park near me has 5mph signs; I've never seen any vehicle
travel that slow, unless manoeuvring into a slot.
My local reuse dump has a 15 kph limit. I find it ridiculous to drive
that slow. I go about 20-25 kph. But beforre the final bump I drive
maybe 3 kph. Otherwise it's uncomfortable. Inside the dump where people
drive and walk, I drive very slowly.
--
Bertel
Kolt, Denmark
Phil
2024-09-22 13:43:47 UTC
Reply
Permalink
Post by Snidely
On Sunday, kami pointed out that ...
Post by kami
Post by Snidely
Post by kami
On Thu, 19 Sep 2024 23:12:52 -0000 (UTC), Christian Weisgerber
I'm sorry, I don't know where to post this.  I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers.  The conversion
factor is... uh...  A 40-year-old calculator book provides a useful
tip:  Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers.  It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
simplest method is to multiply by 0.6
There's no humor in that.
-d
an easier method would be, if the limit is 80 miles per hour,
simply add half, which is 40 and then one tenth of that, which is
4 and multiply it by 2 which is 8, so 48 + 80 is 128 km/h
similarly lets say 120 miles per hour, half 60, tenth times 2 is
12, so 72 + 120 = 192 km/h.
There's no humor in that.
-d
<Loading Image...>
--
Phil B
Snidely
2024-09-22 19:04:02 UTC
Reply
Permalink
Post by Phil
Post by Snidely
On Sunday, kami pointed out that ...
Post by kami
Post by Snidely
Post by kami
On Thu, 19 Sep 2024 23:12:52 -0000 (UTC), Christian Weisgerber
I'm sorry, I don't know where to post this.  I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers.  The conversion
factor is... uh...  A 40-year-old calculator book provides a useful
tip:  Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers.  It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
simplest method is to multiply by 0.6
There's no humor in that.
-d
an easier method would be, if the limit is 80 miles per hour,
simply add half, which is 40 and then one tenth of that, which is
4 and multiply it by 2 which is 8, so 48 + 80 is 128 km/h
similarly lets say 120 miles per hour, half 60, tenth times 2 is
12, so 72 + 120 = 192 km/h.
There's no humor in that.
-d
<https://wesharman.wordpress.com/wp-content/uploads/2013/11/4525f-bkliban001.jpg>
That's a bit better.

-d
--
"First thing in the morning, before I have coffee, I read the obits, If
I'm not in it, I'll have breakfast." -- Carl Reiner, to CBS News in
2015.
Bertel Lund Hansen
2024-09-22 10:51:30 UTC
Reply
Permalink
Post by kami
an easier method would be, if the limit is 80 miles per hour,
simply add half, which is 40 and then one tenth of that, which is
4 and multiply it by 2 which is 8, so 48 + 80 is 128 km/h
I find it easier to multiply by 1.6.

I once gave one of my pupils less than maximum for an answer. The
problem demanded that you do the math approximately. He had calculated
the precise answer in his head and clamid that it was just as quick
(which it was for him). He was displeased with my scoring.
--
Bertel
Kolt, Denmark
Jeff Barnett
2024-09-25 16:06:07 UTC
Reply
Permalink
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
After glancing at the discussion that follows this post, I thought it
appropriate to point out the book "Dimensional Analysis" New Haven: Yale
University Press (1922) by the Nobel Prize winning physicist Percy
Williams Bridgman. It essentially describes and defines physical
dimensions such as distance, speed, energy, force, etc. as well as units
that are defined within a dimension such as meters, feet, and microns as
distances. It shows that dimensions MUST match on both sides of an
equation and, if not, there must be multiplicative constants that have
appropriate dimensions to restore balance. You may define base
dimensions and the others in terms of the base. For example, length,
mass, and time to do mechanics.

Within an equation, you must use the same units everyplace for
quantities in a specific dimension or dimensionless units of conversion
such as 12 inches per foot. It even shows how to determine when physics
equations express nonsense because of unit disparity or non matching
dimensions. The cherry on the cake is discovery of new physical laws via
dimensional analysis.

If you can obtain access to a copy of this book, I recommend taking a
spin through it. A hundred years ago it was novel and educated some very
bright individuals who hadn't quite caught on to what your current
discussion is all about. It wasn't all that obvious way back when. Of
course it was as soon as the subject was systematically presented.
--
Jeff Barnett
J. J. Lodder
2024-09-25 20:46:42 UTC
Reply
Permalink
Post by Jeff Barnett
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
After glancing at the discussion that follows this post, I thought it
appropriate to point out the book "Dimensional Analysis" New Haven: Yale
University Press (1922) by the Nobel Prize winning physicist Percy
Williams Bridgman.
He didn't win the nobel for this book.
(or for his peculiar philosophy of sciece)
It is one of those books that many know exists,
but few will actually have seen it, let alone read any of it.
(don't worry, no loss)
You will need a good old university library to find it,
or you may find a very rare antiquarian copy,
or an almost as rare and by now also antiquarian reprint.
Post by Jeff Barnett
It essentially describes and defines physical
dimensions such as distance, speed, energy, force, etc. as well as units
that are defined within a dimension such as meters, feet, and microns as
distances. It shows that dimensions MUST match on both sides of an
equation and, if not, there must be multiplicative constants that have
appropriate dimensions to restore balance. You may define base
dimensions and the others in terms of the base. For example, length,
mass, and time to do mechanics.
All completely trivial.
What's more, the subject matter has been almost completely forgotten.
All that remains is elementary high school knowledge
of the -conventional- systems of dimensions
that is nowadays associated with the SI.
Few people even know anymore that other systems of dimensions
are possible.
The misconception that a 'dimension' is somehow a property
of a physical quantity is shared nearly universally.
Post by Jeff Barnett
Within an equation, you must use the same units everyplace for
quantities in a specific dimension or dimensionless units of conversion
such as 12 inches per foot. It even shows how to determine when physics
equations express nonsense because of unit disparity or non matching
dimensions.
You may crash Mars landers through non-matching units,
never by non-matching dimensions.
Post by Jeff Barnett
The cherry on the cake is discovery of new physical laws via
dimensional analysis.
Not really. At best it allows you to guess at the form.
The book codifies the obvious.
Dimensional analysis was already well known and understood
through the works of the 19th century greats, such as Kelvin
and Rayleigh.
The use of the so called 'dimensionless numbers',
such as Reynolds', or Froude's number was already well established.
Post by Jeff Barnett
If you can obtain access to a copy of this book, I recommend taking a
spin through it.
A waste of time and perhaps also money, if you don't mind me saying so.
Post by Jeff Barnett
A hundred years ago it was novel and educated some very
bright individuals who hadn't quite caught on to what your current
discussion is all about. It wasn't all that obvious way back when. Of
course it was as soon as the subject was systematically presented.
Already then, Bridgman was belabouring the obvious,

Jan
Jeff Barnett
2024-09-26 04:13:34 UTC
Reply
Permalink
Post by J. J. Lodder
Post by Jeff Barnett
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
After glancing at the discussion that follows this post, I thought it
appropriate to point out the book "Dimensional Analysis" New Haven: Yale
University Press (1922) by the Nobel Prize winning physicist Percy
Williams Bridgman.
He didn't win the nobel for this book.
(or for his peculiar philosophy of sciece)
It is one of those books that many know exists,
but few will actually have seen it, let alone read any of it.
(don't worry, no loss)
You will need a good old university library to find it,
or you may find a very rare antiquarian copy,
or an almost as rare and by now also antiquarian reprint.
Post by Jeff Barnett
It essentially describes and defines physical
dimensions such as distance, speed, energy, force, etc. as well as units
that are defined within a dimension such as meters, feet, and microns as
distances. It shows that dimensions MUST match on both sides of an
equation and, if not, there must be multiplicative constants that have
appropriate dimensions to restore balance. You may define base
dimensions and the others in terms of the base. For example, length,
mass, and time to do mechanics.
All completely trivial.
What's more, the subject matter has been almost completely forgotten.
All that remains is elementary high school knowledge
of the -conventional- systems of dimensions
that is nowadays associated with the SI.
Few people even know anymore that other systems of dimensions
are possible.
The misconception that a 'dimension' is somehow a property
of a physical quantity is shared nearly universally.
Post by Jeff Barnett
Within an equation, you must use the same units everyplace for
quantities in a specific dimension or dimensionless units of conversion
such as 12 inches per foot. It even shows how to determine when physics
equations express nonsense because of unit disparity or non matching
dimensions.
You may crash Mars landers through non-matching units,
never by non-matching dimensions.
Post by Jeff Barnett
The cherry on the cake is discovery of new physical laws via
dimensional analysis.
Not really. At best it allows you to guess at the form.
The book codifies the obvious.
Dimensional analysis was already well known and understood
through the works of the 19th century greats, such as Kelvin
and Rayleigh.
The use of the so called 'dimensionless numbers',
such as Reynolds', or Froude's number was already well established.
Post by Jeff Barnett
If you can obtain access to a copy of this book, I recommend taking a
spin through it.
A waste of time and perhaps also money, if you don't mind me saying so.
Post by Jeff Barnett
A hundred years ago it was novel and educated some very
bright individuals who hadn't quite caught on to what your current
discussion is all about. It wasn't all that obvious way back when. Of
course it was as soon as the subject was systematically presented.
Already then, Bridgman was belabouring the obvious,
Let me start by pointing out that I don't believe I implied that his
Noble Prize was for this book; I know it wasn't. I'm assuming from the
above that you haven't read the book. There is material in it that you
must have skipped or don't remember if you had. By the way, much to my
surprise new paperback copies are available from Amazon for a modest
price. The copy I have was made on a xerox machine 50+ years ago and is
torture to read - every page has a different slant.

It's mostly true that unit mistakes can cause mayhem but so can
dimensional mistakes. I remember helping track down a calculation that
would not balance on Apollo because a newbie engineer didn't realize
that "knots" measured speed, not distance. No harm was done, just a big
waste of time. This is all apropos of the discussion in this thread.
There were other similar mistakes that were common - I suppose these
events (as well as greed) were responsible for the huge people and
project redundancies on Apollo.

Later on in a different world, I invented some unit and dimension
software for the Symbolics Lisp Machines. Dimensions had the status of
data types and units were presentation types. So if you wanted to input,
say an energy, the mouse would highlight and retrieve both erg and joule
values but not numbers that represented forces. The developer could
define the system (e.g. mks or fps) by preferred units as well as the
electrostatic system in play. Conversions were automatic and, assuming
the programmer didn't bitch things up, neither could his users. I
mentioned this stuff to a physicist and was told to go read his copy of
Bridgman.

The book is chuck full of examples that show world class physicist
making unit and dimension errors. It also shows some techniques to avoid
them. And as I said above some new physics was discovered using the
described techniques. Once again, I remind you the book is 100 years
old. The above discussion shows that folks in the arts and sciences are
still making elementary mistakes of the sorts described.
--
Jeff Barnett
J. J. Lodder
2024-09-26 09:56:41 UTC
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Post by Jeff Barnett
Post by J. J. Lodder
Post by Jeff Barnett
Post by Christian Weisgerber
I'm sorry, I don't know where to post this. I'm crossposting to
alt.usage.english, because statute miles as a unit mostly afflict
the English-speaking world.
So you want to convert between miles and kilometers. The conversion
factor is... uh... A 40-year-old calculator book provides a useful
tip: Unless you're designing a space probe, you can use ln(5).
WHAT?
Yes, the natural logrithm of 5 approximates the conversion factor
between miles and kilometers; specifically one mile is about ln(5)
kilometers. It's accurate to four digits.
If nothing else, it's faster to type on a calculator.
I think that's hysterical.
After glancing at the discussion that follows this post, I thought it
appropriate to point out the book "Dimensional Analysis" New Haven: Yale
University Press (1922) by the Nobel Prize winning physicist Percy
Williams Bridgman.
He didn't win the nobel for this book.
(or for his peculiar philosophy of sciece)
It is one of those books that many know exists,
but few will actually have seen it, let alone read any of it.
(don't worry, no loss)
You will need a good old university library to find it,
or you may find a very rare antiquarian copy,
or an almost as rare and by now also antiquarian reprint.
Post by Jeff Barnett
It essentially describes and defines physical
dimensions such as distance, speed, energy, force, etc. as well as units
that are defined within a dimension such as meters, feet, and microns as
distances. It shows that dimensions MUST match on both sides of an
equation and, if not, there must be multiplicative constants that have
appropriate dimensions to restore balance. You may define base
dimensions and the others in terms of the base. For example, length,
mass, and time to do mechanics.
All completely trivial.
What's more, the subject matter has been almost completely forgotten.
All that remains is elementary high school knowledge
of the -conventional- systems of dimensions
that is nowadays associated with the SI.
Few people even know anymore that other systems of dimensions
are possible.
The misconception that a 'dimension' is somehow a property
of a physical quantity is shared nearly universally.
Post by Jeff Barnett
Within an equation, you must use the same units everyplace for
quantities in a specific dimension or dimensionless units of conversion
such as 12 inches per foot. It even shows how to determine when physics
equations express nonsense because of unit disparity or non matching
dimensions.
You may crash Mars landers through non-matching units,
never by non-matching dimensions.
Post by Jeff Barnett
The cherry on the cake is discovery of new physical laws via
dimensional analysis.
Not really. At best it allows you to guess at the form.
The book codifies the obvious.
Dimensional analysis was already well known and understood
through the works of the 19th century greats, such as Kelvin
and Rayleigh.
The use of the so called 'dimensionless numbers',
such as Reynolds', or Froude's number was already well established.
Post by Jeff Barnett
If you can obtain access to a copy of this book, I recommend taking a
spin through it.
A waste of time and perhaps also money, if you don't mind me saying so.
Post by Jeff Barnett
A hundred years ago it was novel and educated some very
bright individuals who hadn't quite caught on to what your current
discussion is all about. It wasn't all that obvious way back when. Of
course it was as soon as the subject was systematically presented.
Already then, Bridgman was belabouring the obvious,
Let me start by pointing out that I don't believe I implied that his
Noble Prize was for this book; I know it wasn't. I'm assuming from the
above that you haven't read the book. There is material in it that you
must have skipped or don't remember if you had.
That is quite possible. I have held a copy in my hands long ago,
and glanced at some of the pages. Enough of them to justify my opinion
expressed here that he is belabouring the obvious with to many examples,
while not expression the general idea of 'dimension' clearly enough.
It may have been a first edition.
Post by Jeff Barnett
By the way, much to my
surprise new paperback copies are available from Amazon for a modest
price. The copy I have was made on a xerox machine 50+ years ago and is
torture to read - every page has a different slant.
It's mostly true that unit mistakes can cause mayhem but so can
dimensional mistakes. I remember helping track down a calculation that
would not balance on Apollo because a newbie engineer didn't realize
that "knots" measured speed, not distance. No harm was done, just a big
waste of time. This is all apropos of the discussion in this thread.
Certainly, no need to inform me about the such problems.
I have wasted some time correcting someone who had used old data,
assuming that 'statvolt' is just an oldfashioned name for 'volt'.
(this is both a unit error and a dimension error)
Post by Jeff Barnett
There were other similar mistakes that were common - I suppose these
events (as well as greed) were responsible for the huge people and
project redundancies on Apollo.
Later on in a different world, I invented some unit and dimension
software for the Symbolics Lisp Machines. Dimensions had the status of
data types and units were presentation types. So if you wanted to input,
say an energy, the mouse would highlight and retrieve both erg and joule
values but not numbers that represented forces. The developer could
define the system (e.g. mks or fps) by preferred units as well as the
electrostatic system in play. Conversions were automatic and, assuming
the programmer didn't bitch things up, neither could his users. I
mentioned this stuff to a physicist and was told to go read his copy of
Bridgman.
I know.
This is automating those crazy American engineering formulae like:

X/[unit of X] = [strange dimensioned constant] times [A / unit of A to
be used] times [B / unit for B] ..... divided by [F/ unit of F]
Post by Jeff Barnett
The book is chuck full of examples that show world class physicist
making unit and dimension errors. It also shows some techniques to avoid
them. And as I said above some new physics was discovered using the
described techniques.
Possibly, but I wouldn't know an example of new physics -derived- in
this way.
All I know about are swindles, rederiving what you know already. [1]
Post by Jeff Barnett
Once again, I remind you the book is 100 years
old. The above discussion shows that folks in the arts and sciences are
still making elementary mistakes of the sorts described.
Of course, there is no end to the mistakes people will make.
By Murphy, the best remedy is not correction afterwards,
but using sane systems beforehand
that makes most of those errors impossible to make.

Jan
--
"Don't tell me what is wrong with the works of others. Do something good
yourself!" (a grumpy old professor I knew long ago)

[1] Typical example: It is sometimes claimed that you can -derive-
the period of a pendulum using dimensional arguments,
as depending on length of the pendulum and small g only.
(and hence independent of amplitude)
This is a typical example of assuming what needs to be shown.
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