Before you are two balls, one solid and one hollow. They are to all appearences completely identical: same size, same weight, same outer material (though one might assume, correctly, that the hollow ball would need a higher-density material on the inside to make it the same weight).

Without breaking either of the balls, how can you easily determine which is hollow?

Assume that the material is solid enough that a hitting the side of the hollow ball will not result in any noticeable echo or vibrations.

I'm afraid the np_rt's equations cannot save him with his inclined plane theory. No matter if one ball is hollow or solid they will both reach the end with the same velocity. At the same time also, assuming that the pitch is the same for both balls but nevertheless there would be no noticeable difference between the two ball's velocities and such. No matter the mass of the balls they will still reach the ground with the same velocity due to the rate of acceleration posed by gravity. Considering the two balls have equal mass, weight, material (so there are no differences in friction) one can't even bring mass as a factor into the equation. Any problems take them up with Galileo biatches!

Posted by dan on 2005-03-26 17:31:00