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On Wed, 24 Sep 2003 20:15:51 GMT, Gene Nygaard
wrote: A balance, by implicit definition again, consists of comparing two masses under the influence of Gravity. Given it is a bridge, in a sense, the constant of Gravity is discarded from both sides and mass is compared only. It is a convenience of earthly expectations (and a defunct system of measurement) that the scale is marked in pounds. The matter of convenience is in the other direction, stupid; we're willing to substitute cheapness for accuracy in what we want to measure on those unreliable bathroom scales. They aren't any more accurate for measuring force than they are for measuring mass on Earth; haven't you ever weighed yourself on your mother's scale or somewhere else and found it differed from yours at home by several pounds? Do you automatically assume you've gained or lost that much weight. I've nowhere introduced the topic of accuracy. It has nothing to do with your original query. Weight and mass can both be measured to considerable accuracy. It all depends on method and standards. A bathroom scale is not a balance. A balance has a scale (the marks along which the balance weights are moved and the markings upon those same weights). However, you do ask for a reference and acknowledge the NIST as a reputable source (many here ignore this commonplace): http://physics.nist.gov/PhysRefData/...constants.html There is absolutely nothing about pounds on this page. So don't be bull****ting us. That is the whole point. You don't see pounds there for mass do you? I don't see pounds as units of mass because this page just lists units in the International System of Units. Exactly. Show me something from NIST saying that pounds are not units of mass. Or from some textbook. That's because pounds are not a unit of mass. They are a unit of weight which is NOT a constant throughout the universe (nor on earth for that matter). Just your say-so? That's the best you can do? I am a trained Metrologist. I have measured mass traceable to the NIST. I have done this in four different Primary and Secondary Standards Labs. I was the head Metrologist of two of them. Have you tried loosing weight? To quote a sge (you know who he is) in this newsgroup: If you huff down a package of Ex-Lax you would take care of the doctor's advice with a lot of "loose" weight. (Language is fun ;-) I suppose that is an affirmative. I can, OTOH, prove that pounds are indeed units of mass. By a reference found at the NIST? I think you would have done that by now if you could. That will prove that you are flat-out wrong in your claim that they are not. Well, I have seen a lot of math tossed over the transom here. But if we are to work by your own standard, cite an NIST reference. Just for practice, consider the troy system of weights. Unlike their avoirdupois cousins, and unlike grams and kilograms, the troy units of weight have never spawned units of force of the same name. They are always units of mass; a troy ounce is exactly 31.1034768 grams, by definition. There is not and never has been any troy pound force or troy ounce force. Hi Gene, Sounds like you proved a pound is not mass. The pages I offered provide a meaningful quote: "The 3d CGPM (1901), in a declaration intended to end the ambiguity in popular usage concerning the word "weight," confirmed that: The kilogram is the unit of mass..." Any other usage of "weight" in regard to the sensation of the action of Gravity upon an amount of mass is outdated by more than a century of understanding and convention. 73's Richard Clark, KB7QHC |
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