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Re: Weight and Mass



From: Hugh Haskell <hhaskell@MINDSPRING.COM>

weight = the gravitational force on an object due to Earth

mass = the quantity of material present in a sample; fundamentally
related to the number of atoms in the sample

I agree that this is the "quick and dirty" definition of weight, but
we often use the word "weight" in the sense of the force we would
exert on a scale place under our bottom. In other words, we refer to
astronauts in orbit as "weightless" even though the force of the

I firmly ban such terminology from day one. See below.

microscopic, and udetectable by the body. Furthermore, even the
common definition you mention is not exact. The thing we call the

On the contrary, it is exact as it can possibly be. The contact force under our feet, given by a bathroom scale, is *sometimes* numerically equal to your *weight*, but it is not alway so.

force of gravity of the earth, as it is normally used, that is, the
reading of a scale when both scale and user are at rest and firmly
planted on the earth, includes the effects of the earth's rotation on
that reading, which varies with latitude.

What we need to do is change the concept of *normally used*. Terminology is sufficiently bastardized so as to introduce a great many unnecessary complications. Better to pick one, the correct one, and stick with it no matter what. Many textbooks are finally getting this clue.


Cheers,
Joe

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