On Tue, 30 Sep 2003 14:21:14 -0700, Jim Kelley
wrote:

Gene Nygaard wrote:
It doesn't cost you any more to pay attention.

Repeat to yourself until you understand it: Weight is an AMBIGUOUS
word. IT HAS SEVERAL DIFFERENT MEANINGS.

What cause have I given you to write to me in such a manner?

The one you cite from the Chemical Rubber Company is, of course, one
of those several definitions. If it always meant the same as mass in
physics jargon, I wouldn't have to point out to you that this is an
ambiguous word, would I?

This is the first you've mentioned anything about it being ambiguous.

You just haven't been paying attention.

Until now, you've just been belligerent and accusational about it.

Didn't you read the message you responded to, especially what
immediately followed the sentence you quoted? Didn't you see what
NIST and ASTM have to say about this? Look at it again, and read it
slowly this time

I'm commenting on what you said, Gene. I have no comment on what NIST
had to say.

Thus the SI unit of the quantity weight used in this
sense is the kilogram (kg) and the verb "to weigh" means
"to determine the mass of" or "to have a mass of".

Examples: the child's weight is 23 kg

Learn to evaluate your sources, also. Those sources are more credible
than any CRC Handbook on this subject.

You need to learn how to attribute yours. I didn't write that. :-)

There isn't any standard way of handling this, as far as I know. I've
seen it done several different ways, none of them completely
satisfactory. So I'm open to suggestions, if you can tell us how you
think it should be done. Next time I'll mark the end of the quote
from an earlier message, as well as the beginning--would that satisfy
you?

Your definition of weight is not the proper one to use for your body
weight in the doctor's office or the gym.

I don't write definitions. But the ones I have cited are no less
accurate in the doctors office than the physics lab.

They are incorrect in the doctor's office, and even more incorrect in
the supermarket or the jewelry store. Like I said, you don't have to
call the quantities used there "weight"--but if you do call them
weight, use the definition which is correct in that context. Don't
misinterpret what is being used there.

You can, of course, choose not to call this quantity "weight." You
can call it mass instead, if you want to.

As I recall, the argument was about whether to call it a mass or a
force.

You recall incorrectly.

It's generally accepted that weight is a force.

I've shown in this thread from the experts in the field, including
NIST (the U.S. national standards agency) and ASTM (an industry
standards agency) and NPL (the U.K. national standards agency) and the
Canadian Standard for Metric Practice, that this is false. All of
these sources and many others tell you that weight is an ambiguous
word, with several different meanings.

Problems can arise when
someone claims a mass is a force and vice versa.

I agree.

Furthermore, it is not an acceptable option to misinterpret what they
are saying, and to misapply an inappropriate definition of weight.

It is possible that you are doing some of the misinterpreting.

You could, of course, argue that we should all change to your usage.

Many people already have, obviously.

Not very many, surprisingly. It is much more common to find people
claiming, erroneously, that there is some error in that usage.

Reflecting the apparent dichotomy, the CRC defines the pound both ways:
"1. A unit of mass equal in the U.S. to 0.45359237 kg. exactly.
2. Specifically, a unit of measurement of the thrust or force of a
reaction engine representing the weight the engine can move, as an
engine with 100,000 pounds of thrust. 3. The force exerted on a one
pound mass by the standard acceleration of gravity."

That really shouldn't come as any surprise to you, does it, at this
stage of the game?

I believe I had stated the same thing in so many words, earlier.

Interestingly, they also define poundal, pound mass and pound weight.
No mention of pound force. Evidently, that would be redundant. ;-)

Have you figured out yet what those poundals are, and how they are
used?

Were you not able to ascertain that from my earlier post where I
referenced the definition in Halliday and Resnick?

No, I couldn't tell one way or the other from your mere statement that
the poundal was idenitified in that appendix as a unit of force
whether or not you know anything about the system in which they are
used. Like slugs, poundals only exist in one limited purpose system
of mechanical units, mostly used to simplify calculations. Do you
understand how these systems are used, and the difference between
them.

The part you snipped (the second sentence in the last paragraph of
mine quited above) makes it clearer that this is what I was asking
about. So tell me now, what is the base unit of mass in the system in
which poundals are the derived unit of force? Do you understand that
yet? I still don't know.

Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/