Units of measurement

[drcampbell]

... Why define the units of one measurement system in terms of another instead of just using the other?

So that you have only ONE fundamental reference standard. In this case, the wavelength of the cesium spectral line.

I'd suggest that it does, in the sense that there is a very strong impetus to use the same system of units as your suppliers. If everyone around you uses inches, then you are pretty much forced to use inch measurements, or you will be subject to inflated costs associated with getting stuff custom made, smaller production runs, etc. ...

You and Besoeker are both making the same mistake: The excess cost is the result of MAKING widgets to cardinal dimensions of two or more measurement systems and maintaining an inventory, not a result of MEASURING them. It costs nothing to LABEL a bearing "50.8 mm". (there will be some cost & chaos because there will be both 50 mm and 50.8 mm bearings on the shelf)

... One of the reasons that the US gets away with sticking with inches is that they are such a large economy that it doesn't hurt them as much to buck the rest of the world. ...

This conventional wisdom is being proved wrong every day. Maybe it doesn't hurt small American businesses with limited international operations much, but it does hurt. And many American businesses have already made the conversion or are in the process of converting. The car biz, for example, is almost completely SI now and has been for maybe twenty years.

The conversion from computer-aided drafting to computer-aided design has helped, too. Once a CAD model is created, one can take measurements from it in any system at all -- SI, British, FFF, whatever. And when a CAD model is delivered directly to a CAM machine, it's completely hands-off -- human-out-of-the-loop.

...There is a huge political component in the selection ... the 'perfect' system of units would go nowhere because we don't have the political base.

Sad but true.

 

[Besoeker]

So that you have only ONE fundamental reference standard.

Yet despite that, you have two systems of measurement units.
That is my very simple point.

 

[Besoeker]

S
You and Besoeker are both making the same mistake: The excess cost is the result of MAKING widgets to cardinal dimensions of two or more measurement systems and maintaining an inventory, not a result of MEASURING them. It costs nothing to LABEL a bearing "50.8 mm". (there will be some cost & chaos because there will be both 50 mm and 50.8 mm bearings on the shelf)

Who mentioned excess cost??
At least you accept there will some cost.
And what about the bearing manufacturers? Having to set up for manufacture of two different sizes.

 

[MAC702]

Um NO.

From my opening post:



And I already knew, as I stated a few posts ago, the the inch had been redefined as 25.4 mm.

It looked as if you were disagreeing with the definition of inch.

So you're only complaint with my post is that we don't insist on calling it SI, still?

Learn to be a little more flexible. You'll live longer. And you'll be able to sell your International Metric System easier.

We all know the Metric System is the SI system. It can be called two different things without a problem.

You are on the wrong Internet and profession if you insist on one and only official name for something, across the globe no less.

Have you any idea how any different things on an electrician's cart can be called a "red head," depending on which electrician you talk to? Now THAT's when things can get confusing.

 

[Besoeker]

It looked as if you were disagreeing with the definition of inch.

So you're only complaint with my post is that we don't insist on calling it SI, still?

No disagreement and no complaint.

Learn to be a little more flexible. You'll live longer. And you'll be able to sell your International Metric System easier.

It isn't mine to sell.

We all know the Metric System is the SI system. It can be called two different things without a problem.

You can call it whatever you want to. I know what it correctly called.

You are on the wrong Internet and profession if you insist on one and only official name for something, across the globe no less.

Do you have more than one name for the Ampere?

Now, can we chill?
What's your favourite beer?

 

[Russs57]

I think, for several decades now, SI units have been commonly used in the engineering, scientific, and medical community in USA.

Of course we also did stuff in our normal units of measurement. Typically it was harder but in some cases it was easier (don't ask me to give an example).

Now be honest visitor. Aren't you acquainted with terms like slug, blob, and slinch? You know, as in one blob equals 12 slugs.

Darned if I ever bothered to understand the UK money system. And don't get me started on British Whitworth threads. Of course those in glass houses shouldn't throw stones. BTW, how many stones in a tonne?

Oh, I like Stouts, then Porters. But I won't turn down a Bass or Newcastle.

 

[Phil Corso]

Mac702, Russs57...

Sorry fellas, but metric and SI-units are not the same! The Si-units are built around 7 base quantities: 1) length, 2) mass, 3) time, 4) electric current, 5) temperature, 6) luminous intensity, and 7) amount of a substance. None, repeat none, are based on any USA-used measurements!

They, in turn, give rise to 7 base units, which are: a) the meter, b) the kilogram, c) the ampere, d) the second, e) the kelvin, f) the candela, and g) the mole! All 7, are expressed with specific tests, some seemingly unrelated to their alluded to "function"! Ampere, for example, is actually derived from a test involving mechanical force!

Then, other units can be derived to express physical quantities, like, power, force, magnetic flux, etc! Furthermore, some, like Energy, Newton, Force, have special names!

Here are two other questions:

1) Why are some units of measurement capitalized, while others aren't?

2) What's the difference between Engineering-notation and Scientific-notation?

BTW, Russ... what's a normal unit of measurement?

Regards, Phil Corso

 

[peter d]

I know I have brought this topic up before.
Will the US ever join the rest of the world and move to using SI units of measure?
For example, is there any sense in two different units for power?

And AWG is baffling in its derivation.

https://en.wikipedia.org/wiki/American_wire_gauge

Hopefully not. :happyno:

 

[electrofelon]

You can pry my hogshead of whiskey from my cold dead hands

 

[Russs57]

Phil, because they are named after people. Of course if we were, say French, we would not do so. I find temperature interesting as we always say degrees but in capitol F, C, K, etc.

Maybe better to ask about prefixes like femto and Peta. There one could reasonably take exception to deca, hecto, and kilo. I trust that this also answers question #2 as engineers wouldn't bother with deca and hecto and would instead stick to powers in increments of three.

By normal I was merely taking a short cut in language to refer to units that Americans typically used such as the inch.

 

[Russs57]

Now if you are going to mention hogshead I think you need to spell it as Whisky and not Whiskey.

 

[MAC702]

Mac702, Russs57...

Sorry fellas, but metric and SI-units are not the same! ....

Here are two other questions:...

I apologize that my only point has been clouded and unrecognized. I'll pass on the questions. My first degree was in physics.

 

[Phil Corso]

Russs57...

Fahrenheit, Celsius, and Kelvin were names of the men that discovered/uncovered temperature relationships!

Phil

 

[Besoeker]

Mac702, Russs57...

Sorry fellas, but metric and SI-units are not the same!

A breath of common sense.
Did you like my Cortina brochure?

 

[Phil Corso]

Besoeker...

Although an American, we have a child born "a cockney"! So, I understand your humor! Unfortunately, it's sad that others don't! BTW, the only thing I found wanting in Great Britain was a "roof!

Phil

 

[Besoeker]

I think, for several decades now, SI units have been commonly used in the engineering, scientific, and medical community in USA.

Of course we also did stuff in our normal units of measurement. Typically it was harder but in some cases it was easier (don't ask me to give an example).

Now be honest visitor. Aren't you acquainted with terms like slug, blob, and slinch? You know, as in one blob equals 12 slugs.

Darned if I ever bothered to understand the UK money system. And don't get me started on British Whitworth threads. Of course those in glass houses shouldn't throw stones. BTW, how many stones in a tonne?

Oh, I like Stouts, then Porters. But I won't turn down a Bass or Newcastle.

Interesting compilation there.

Yes, I'm acquainted with slugs and related units. That I never use. My father could set his spreader to an accurate number of bushels per acre.
The UK money system is exactly like yours. The major unit is the pound sterling (£) and the sub unit is the penny as p. And 100p = £1. Much like you have 100 cents in a $. What's so difficult to understand about that?

How many stones in a tonne? Trick question?
= 160 stones.
In Imperial

14lbs = 1 stone
8 stones is one cwt (hundredweight)
20 cwt = one ton (not tonne)
So 1 ton = 160 stones.

The SI tonne is 2205 lbs which would be 157.5 stones.

 

[Carultch]

Now if you are going to mention hogshead I think you need to spell it as Whisky and not Whiskey.

If the country of origin has an E in its name, it ends in EY. UnitEd StatEs, England, IrEland.
If the country of origin doesn't have an E in its name, it ends in Y. Canada, Scotland, Japan.

 

[Carultch]

1) Why are some units of measurement capitalized, while others aren't?

If it is named after a proper noun, it is capitalized. Usually a person's name (Newton, Watt, Joule, Celsius, Kelvin, etc). If it is not named after a proper noun, like meter, second, gram, etc, it is lowercase.

SI Prefixes are generally capitalized if greater than 1, although kilo is the exception as both k and K may represent it. And lowercase if less than 1.

 

[Besoeker]

If it is named after a proper noun, it is capitalized. Usually a person's name (Newton, Watt, Joule, Celsius, Kelvin, etc). If it is not named after a proper noun, like meter, second, gram, etc, it is lowercase.

SI Prefixes are generally capitalized if greater than 1, although kilo is the exception as both k and K may represent it. And lowercase if less than 1.

kW, not KW.

 

[K8MHZ]

If it is named after a proper noun, it is capitalized. Usually a person's name (Newton, Watt, Joule, Celsius, Kelvin, etc). If it is not named after a proper noun, like meter, second, gram, etc, it is lowercase.

SI Prefixes are generally capitalized if greater than 1, although kilo is the exception as both k and K may represent it. And lowercase if less than 1.

Lowercase l = liter

Uppercase L = Inductance in henries.

Upper case H = henry (written in lowercase, but referring to Joseph Henry)

"The International System of Units (SI) specifies to write the symbol of a unit named for a person with an initial capital letter, while the name is not capitalized in sentence text, except when any word in that position would be capitalized, such as at the beginning of a sentence or in material using title case."

Purposeful confusion?