TITLE: Measuring mass by acceleration due to electromagnetic forces in free fall
QUESTION [1 upvotes]: My question is a simple one (I think):
How precise will the results be if you attempt to measure the mass of a macroscopic object by measuring it's acceleration when a constant electromagnetic force is applied to it?
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This is an entirely hypothetical question. And when I said macroscopic, I actually meant something with a mass around a kilgram (give or take a few orders of magnitude)

REPLY [2 votes]: You could probably make this precise to about 1e-7 to 1e-8, or so, maybe better, if you are willing to invest more money than is needed for a tabletop experiment, i.e. with an experiment on a satellite. A very good absolute gravimeter, like this one http://www.microglacoste.com/fg5xspecs.php achieves almost ppb precision, which is mostly limited by environmental noise (these instruments pick up the motion of the moon, tides and minute geological changes resulting in noise). The question is... what are you trying to measure, and is there a better way to achieve the same or a better result? Often there are smarter ways to set limits in physics than with a direct measurement.
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