Asked in SciencePhysicsChemistryAtomic Mass
What tool is used to determine mass?
September 10, 2013 10:34PM
Most often on Earth, either a pan-balance or a scale is used. As long as you stay on
the same planet and know the acceleration of gravity there, the easiest method is to
measure weight, and then calculate mass from it.
You just have to remember that if you go to another planet, the weights of all the masses
will change, so you'll have to know the acceleration of gravity in the place where you are.
You'd have to be extra careful in space. If your spacecraft is coasting, then nothing in
it has any weight. And during a rocket-engine burn, or if it's falling toward a planet, the
weight of things inside depends on the rate of acceleration. If there's any acceleration
at all, then you could use a pan balance to compare your unknown object against the
marked, standard masses that you carry in a little felt-lined mahogany box. But you
can't use a plain old bathroom scale at all in space, because it's calibrated for gravity
on Earth. So it would read some number if you're accelerating, but the number wouldn't
tell you anything.