Author Topic: Use of Metric Units  (Read 5395 times)

Offline Surfdaddy

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Re: Use of Metric Units
« Reply #20 on: 11/21/2022 10:56 pm »
The US was heading for metric in the late 70's/early 80s but then *ahem* a new President decided that we weren't going to do that.

So instead we just crashed a probe on Mars and continue to be an oddity in the world (in other ways as well).

Online JayWee

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Re: Use of Metric Units
« Reply #21 on: 11/22/2022 01:12 am »
Fast forward.  I understand metric.  My biggest stumbling block is going from lbs of thrust to whatever metric is used.  I understand that 1 bar is atmospheric pressure.  I understand tons of pressure metric.  It is the Pascals, Newtons, and kilopascals that confuse me in translation to an English equivalent. 
As a non-USian, I find the many variants of pounds the most confusing (with short/long tons slightly behind).  (And don't get me started on cups-vs g/ml in recipes).

Online spacenut

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Re: Use of Metric Units
« Reply #22 on: 11/22/2022 02:13 am »
Most kitchen measuring cups and items these days are printed in both English and the Metric system. 

Online JayWee

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Re: Use of Metric Units
« Reply #23 on: 11/22/2022 02:33 am »
Most kitchen measuring cups and items these days are printed in both English and the Metric system. 
It's more the idea of measuring by volume something I'm used to measure by mass over here.

Offline Proponent

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Re: Use of Metric Units
« Reply #24 on: 11/22/2022 11:40 am »
In the early 1900's the Senate by one vote, decided not to convert to the metric system.  It would have been far easier then.

That's interesting and surprising. Do you have a reference?

I cling to a faint hope that US adoption of SI units may get easier with time as measuring instruments, e.g., scales, become digital and as flexible manufacturing technologies such as 3D printing are introduced.

EDIT: typo
« Last Edit: 11/22/2022 08:48 pm by Proponent »

Offline Proponent

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Re: Use of Metric Units
« Reply #25 on: 11/22/2022 11:51 am »
As a non-USian, I find the many variants of pounds the most confusing (with short/long tons slightly behind).  (And don't get me started on cups-vs g/ml in recipes).

In the distant past, variations of the pound included the tower pound (the basis of the British currency originally being a tower pound of silver), the troy pound (a relative of the troy ounce still used for precious metals) and the pound avoirdupois, but to my knowledge only the last is still in use. Do you have examples to the contrary?

Offline Proponent

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Re: Use of Metric Units
« Reply #26 on: 11/22/2022 03:03 pm »
It's more the idea of measuring by volume something I'm used to measure by mass over here.

Perhaps I'm barking up the wrong tree, but if you're referring to the ounce markings on kitchen measuring devices, those are actually volume units -- to wit, fluid ounces. A US fluid ounce is 1/128 of a US gallon, which in turn is 231 in3. A US fluid ounce of water weighs a bit more than 1 ounce. An imperial fluid ounce, on the other hand, is 1/160 of an imperial gallon. The original definition of the imperial gallon being the volume of water weighing 10 pounds (160 ounces), an imperial fluid ounce if water weighs 1 ounce with some precision.

But the only thing that really matters is that an imperial pint (of beer, of course), being 20 imperial fluid ounces, is nearly 25% larger than a US pint of 16 US fluid ounces.

Online DanClemmensen

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Re: Use of Metric Units
« Reply #27 on: 11/22/2022 04:14 pm »
It's more the idea of measuring by volume something I'm used to measure by mass over here.

Perhaps I'm barking up the wrong tree, but if you're referring to the ounce markings on kitchen measuring devices, those are actually volume units -- to wit, fluid ounces. A US fluid ounce is 1/128 of a US gallon, which in turn is 231 in3. A US fluid ounce of water weighs a bit more than 1 ounce. An imperial fluid ounce, on the other hand, is 1/160 of an imperial gallon. The original definition of the imperial gallon being the volume of water weighing 10 pounds (160 ounces), an imperial fluid ounce if water weighs 1 ounce with some precision.

But the only thing that really matters is that an imperial pint (of beer, of course), being 20 imperial fluid ounces, is nearly 25% larger than a US pint of 16 US fluid ounces.
You are indeed barking up the wrong tree. An American cook uses a measuring cup. A European cook uses a scale and actually measures the mass. A kitchen scale is rarely used in the US.

Offline Barley

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Re: Use of Metric Units
« Reply #28 on: 11/22/2022 04:52 pm »
It's more the idea of measuring by volume something I'm used to measure by mass over here.

Perhaps I'm barking up the wrong tree, but if you're referring to the ounce markings on kitchen measuring devices, those are actually volume units -- to wit, fluid ounces.
Etymologically "ounce" comes from the Latin for a twelfth part, thence a generic sub-unit.  It has the same root as "inch", a twelfth part of a foot.  Which is why it shows up as several different units.  It's a small mercy that the sound shifts to get to "inch" and "ounce" were different.

It's similar to "minute" -- a small part of ...; "second" which is short for "second minute" -- a small part of a small part of ...; or "k", "mil" and "thou" which are used in many different contexts with an implicit base unit.
« Last Edit: 11/22/2022 04:55 pm by Barley »

Offline Airlocks

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Re: Use of Metric Units
« Reply #29 on: 11/22/2022 05:05 pm »
Quote
so none of this km/h nonsense. Metres per second PLEASE.


It is NOT nonsense. My Fiant Grande Punto max speed (when it was much younger) is 175 km/h, and certainly not... (Google convertor) 48.615 m/s.


We could compromise on angstroms per annum?

Angtrom per an*us... per what ?
Professor Pangloss: a SpaceX die-hard supporter. 
https://www.britannica.com/topic/Pangloss

Offline Barley

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Re: Use of Metric Units
« Reply #30 on: 11/22/2022 06:02 pm »
I grew up using the English system.  We learned about the metric system, but that is about it in high school.  I still used English in physics in high school.  It was still used when I went to college. 

Fast forward.  I understand metric.  My biggest stumbling block is going from lbs of thrust to whatever metric is used.  I understand that 1 bar is atmospheric pressure.  I understand tons of pressure metric.  It is the Pascals, Newtons, and kilopascals that confuse me in translation to an English equivalent. 

For instance 7.5 million lbs thrust of Saturn V can be translated into would be about 3,402 tons of pressure in Metric.  What should that read in metric?  33,362.9 kilonewtons?  Or, a 30,000 lb thrust engine to what in metric? About 13.6 metric tons?  133.4 kN?  Both seem off when roughly translating.
There are at least two different units called "pound" (abbreviated "lb") measuring different physical phenomenon. You are not distinguishing between them.  Your confusion has nothing to do with "metric".

Generations of engineering professors have dedicated their lives to propagating this confusion.  I was encouraged when talking with a recent graduate engineer who said he was told to rip the databook in half and throw out the English Engineering Units section.  Finally after two hundred years.

Offline Comga

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Re: Use of Metric Units
« Reply #31 on: 11/23/2022 06:27 pm »
Fast forward.  I understand metric.  My biggest stumbling block is going from lbs of thrust to whatever metric is used.  I understand that 1 bar is atmospheric pressure.  I understand tons of pressure metric.  It is the Pascals, Newtons, and kilopascals that confuse me in translation to an English equivalent. 
As a non-USian, I find the many variants of pounds the most confusing (with short/long tons slightly behind).  (And don't get me started on cups-vs g/ml in recipes).

Did you know that there are two definitions if the foot?
There is a “standard” foot defined as 0.3048 meters.
There is (for the last century and for another five weeks) the “survey foot”, which is about 8 parts per million larger.  IIRC
It turns out if one surveys the continental US from coast to coast using “standard feet” the result would be off by about 15 meters.
In an infinitesimal sign of of progress, the survey foot will be abandoned at the end of 2022 as the result of one man’s decades long crusade.
This crap goes on forever.
« Last Edit: 11/23/2022 06:28 pm by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online Phil Stooke

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Re: Use of Metric Units
« Reply #32 on: 11/23/2022 06:44 pm »
"There are at least two different units called "pound" (abbreviated "lb") measuring different physical phenomenon."

That's your problem right there.  And though the problem might have nothing to do with metric, the solution does.

Back to Apollo for a moment:
"146:43:52 Schmitt: ... This rock is about 3 meters in diameter, but it's one of the flat-surfaced rocks. It only stands about - at the most - one-third of a meter high."

(from the Apollo Lunar Surface Journal at Apollo 17 Station 5)

While on the Moon the astronauts often used metric units to describe distances and sizes.  They were not entirely consistent.  But it really is atrocious that we don't even get metric equivalents in our current Artemis reporting.

Online Hobbes-22

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Re: Use of Metric Units
« Reply #33 on: 11/23/2022 08:35 pm »
It used to be worse. This is a cabinet that contains sets of weights. Every drawer is a different set: every city had its own standards.
Photo taken at the Science Museum in London earlier this year.

Offline laszlo

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Re: Use of Metric Units
« Reply #34 on: 11/24/2022 11:48 am »
Back to Apollo for a moment:
"146:43:52 Schmitt: ... This rock is about 3 meters in diameter, but it's one of the flat-surfaced rocks. It only stands about - at the most - one-third of a meter high."

(from the Apollo Lunar Surface Journal at Apollo 17 Station 5)

While on the Moon the astronauts often used metric units to describe distances and sizes.  They were not entirely consistent.  But it really is atrocious that we don't even get metric equivalents in our current Artemis reporting.

Schmitt is a PhD geologist so his natural language when doing fieldwork was metric. As LM Pilot, his dialogue with the AGC, LM Commander and MCC CAPCOM was all in feet, etc.

So the units used were at least situational, flight vs. geological fieldwork, and were also determined by the background and preferences of the individual astronaut.

Perhaps what we need is something similar to the Canadian attitude towards language - the need to be fluent in multiple flavors.

Offline Barley

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Re: Use of Metric Units
« Reply #35 on: 11/24/2022 01:00 pm »


Did you know that there are two definitions if the foot?
There is a “standard” foot defined as 0.3048 meters.
There is (for the last century and for another five weeks) the “survey foot”, which is about 8 parts per million larger.  IIRC
It turns out if one surveys the continental US from coast to coast using “standard feet” the result would be off by about 15 meters.
In an infinitesimal sign of of progress, the survey foot will be abandoned at the end of 2022 as the result of one man’s decades long crusade.
This crap goes on forever.

The difference is 2 parts per million.  999,998 survey feet are 1,000,000 international feet.  Both feet are defined as rational fractions of a meter, so the relationship is exact.

But at least part of the problem is not metric v. customary per se.  It's the attitude of users, particularly self-appointed authorities (as opposed to actual authorities such as NIST).

The definition of the liter changed by 28 parts per million in 1964 and while some people noticed at the time it is now long forgotten.  The French changed their definition of a "billion" by a billion parts per million and now insist it never happened.

This crap goes on forever only because engineering professors have tenure; corrupt the minds of a generation of young people; and then select the next generation of people who will have tenure.  If Joseph Dombey had arrived in 1794 and the US went metric these academics would have screwed with the metric system.  The "kilogram of water" liter would not have gone down without a fight.




Offline dror

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Re: Use of Metric Units
« Reply #36 on: 11/24/2022 01:12 pm »


Did you know that there are two definitions if the foot?
There is a “standard” foot defined as 0.3048 meters.
There is (for the last century and for another five weeks) the “survey foot”, which is about 8 parts per million larger.  IIRC
It turns out if one surveys the continental US from coast to coast using “standard feet” the result would be off by about 15 meters.
In an infinitesimal sign of of progress, the survey foot will be abandoned at the end of 2022 as the result of one man’s decades long crusade.
This crap goes on forever.

The difference is 2 parts per million.  999,998 survey feet are 1,000,000 international feet.  Both feet are defined as rational fractions of a meter, so the relationship is exact.

But at least part of the problem is not metric v. customary per se.  It's the attitude of users, particularly self-appointed authorities (as opposed to actual authorities such as NIST).

The definition of the liter changed by 28 parts per million in 1964 and while some people noticed at the time it is now long forgotten.  The French changed their definition of a "billion" by a billion parts per million and now insist it never happened.

This crap goes on forever only because engineering professors have tenure; corrupt the minds of a generation of young people; and then select the next generation of people who will have tenure.  If Joseph Dombey had arrived in 1794 and the US went metric these academics would have screwed with the metric system.  The "kilogram of water" liter would not have gone down without a fight.

I 3/8 agree with you !
(Or is it 5/16? 🤔)
Whichever is bigger !!
Space is hard immensely complex and high risk !

Offline TrevorMonty

Re: Use of Metric Units
« Reply #37 on: 11/24/2022 04:54 pm »


Back to Apollo for a moment:
"146:43:52 Schmitt: ... This rock is about 3 meters in diameter, but it's one of the flat-surfaced rocks. It only stands about - at the most - one-third of a meter high."

(from the Apollo Lunar Surface Journal at Apollo 17 Station 5)

While on the Moon the astronauts often used metric units to describe distances and sizes.  They were not entirely consistent.  But it really is atrocious that we don't even get metric equivalents in our current Artemis reporting.

Schmitt is a PhD geologist so his natural language when doing fieldwork was metric. As LM Pilot, his dialogue with the AGC, LM Commander and MCC CAPCOM was all in feet, etc.


While I work in metric still occasionally describe rough distances in feet and inches eg "few feet away".

Fishman still like to use pounds instead of kgs as number is bigger and sounds more impressive  eg 10lbs vs 5kgs.


Offline Comga

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Re: Use of Metric Units
« Reply #38 on: 11/24/2022 05:08 pm »


Back to Apollo for a moment:
"146:43:52 Schmitt: ... This rock is about 3 meters in diameter, but it's one of the flat-surfaced rocks. It only stands about - at the most - one-third of a meter high."

(from the Apollo Lunar Surface Journal at Apollo 17 Station 5)

While on the Moon the astronauts often used metric units to describe distances and sizes.  They were not entirely consistent.  But it really is atrocious that we don't even get metric equivalents in our current Artemis reporting.

Schmitt is a PhD geologist so his natural language when doing fieldwork was metric. As LM Pilot, his dialogue with the AGC, LM Commander and MCC CAPCOM was all in feet, etc.
While I work in metric still occasionally describe rough distances in feet and inches eg "few feet away".

Fishman still like to use pounds instead of kgs as number is bigger and sounds more impressive  eg 10lbs vs 5kgs.

It’s 11 lb vs 5 kg! 😉
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline hpras

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Re: Use of Metric Units
« Reply #39 on: 11/24/2022 05:19 pm »
I am a Canadian in my mid-50's....  this is how we roll.

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