Mass vs Weight
Date: Around 1993
Is the unit of measure of weight a gram? It appears to be trivial
but it is used in this context on the `IGAP' test. What gives?
Strictly speaking a gram is a unit of mass. However, it can be
used as a unit of weight in the sense "however much a gram of matter weighs",
which is about the same everywhere on the surface of the earth. If you think
about it, there are almost no circumstances when a person would use the word
"weight" and really mean weight. They do not care if the object being
referred to as weighing 100 pounds (or grams) is on the earth or on the moon -
what they are really doing is using "weight" to mean mass. Which is fine with
everybody, since everybody understands it the same way.
If "weight" means "the force due to gravity" then I suppose one
would measure it in terms of units of force, which would be Newtons in MKS and
dynes in CGS units.
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Update: June 2012