Units of Measure

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Gary
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Units of Measure

Post by Gary » Tue Sep 18, 2012 7:40 pm

It's been my understanding that the gram is a unit of measure of the amount of mass that comprises a body as opposed to weight, because weight is actually a measure of the pull of gravity. Therefore, an item with a measurement of NN grams on earth will still read NN grams on the moon, whose gravitational pull is one-seventh that of the earth. Also, that same object may weight X pounds on earth but will weigh Y pounds on the moon.

The reason I'm asking is that on an automotive forum (where I'm a member) people have been discussing pistons weighing NN grams and their needing to shave some material so the rotating assembly is balanced. When I stated grams are a measure of mass and not weight, well all hell broke loose with some people stating I was wrong and that it didn't matter. Well, if something is to balance then it stands to reason that the amount of material should be consistent for proper operation.

Some cursory searches on the InterWeb Thingy produced links that stated the gram is a measure of weight. :wtf: :wtf:

When did this happen? Grams as a unit of mass was drilled into us by two different high school teachers as well as a college instructor.
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RJDiogenes
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Re: Units of Measure

Post by RJDiogenes » Wed Sep 26, 2012 12:01 am

Well, grams and its multiples are definitely used as a measure of weight. According to the Wiki page, it measures mass. According to the Wiki page on mass, there is inertial mass and gravitational mass. What this exactly means, I don't know. I'm guessing that for purposes of measurement on the surface of the Earth, there is equivalence.
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