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.

(In reply to correction by dan)

Acutally Galileo would be happy because the final speed only depends on the shape of the ball (not the mass).

The solid bal can be lighter or heavier than the hollow one, but it allways rolls down a hill faster .

Edited on March 29, 2005, 5:47 pm

Posted by ajosin on 2005-03-29 12:06:01