This is related to the electromagnetic idea (or is it the same?): couldn’t you accelerate the mass and keep at it–presuming it stays in one piece–until it is reduced to its ultimate subatomic particles, and do a simple E=mc^2?
Actually all of am77494, and all other mass measurements, are of course E=mc^2-able. Just getting the right hammer for the nail.
Your definitions of “stays in one piece” and “reduced to its ultimate subatomic particles” can’t both be the ones I’m used to.
Well, I meant before the crack(s) up. But couldn’t you do additive analyses? (Real question.)
That works if and only if the object floats.
If the object sinks, the displaced water is only equal to the object’s volume, not the object’s mass.
Since we’re discussing weightless environments, there’s no such thing as “floats”.
This is what i was thinking, something like a bow and arrow where you know the stored energy.
This is basically what the Skylab device does (as described by Stranger). Only measuring acceleration directly is kind of hard to do accurately, so it’s easier to let the spring go back and forth, first pushing the mass and extending, then contracting back and pulling the mass, and measure the total time it takes to go through a cycle. You’re still measuring acceleration, but when you do it going both ways, it’s easier to measure accurately.
Again, it’s only accurate as long as you’ve got a big “immovable” object to attach the other end of the spring to.