What explanation is given under A. Newtonian gravity and B. General relativity for the fact that in the absence of atmospheric influences, bodies of different mass fall at equal rates. It's so counterintuative and I can't seem to locate an answer!
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Actually, it's very normal for similar materials of different amounts of mass to fall at the same rate (ignoring air resistance, of course). To see that, simply imagine dropping two dimes, once where the dimes are fused together, and once where they aren't. Would you expect them to fall differently in those two situations? Certainly not, so it's obvious that mass should not affect the rate of fall.
What is actually surprising is that the material doesn't affect the rate of fall-- nickel falls just like wood or plastic. That is not the normal state of affairs for other forces, they always depend on the material. Newton's explanation is that it is mass that creates and responds to gravity-- any kind of mass, regardless of material.
Einstein's explanation is that gravity is not a force, it is a geometric effect on spacetime, but even so, the degree to which gravity affects spacetime only depends on mass, and of course the path an object takes through spacetime will not depend on the mass or material that an object is made of.
Ken G
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