I'm pretty sure that *if* we were just talking about the dynamical behavior of a bowling ball moving through a vacuum, then it would have behavior isomorphic to any other shape/density with the identical inertia matrix. (There would be a brick of uniform density, of unique proportions that has this property.) But when friction with the bowling alley is considered, I suspect funny other things can happen. E.g., what if the bowling ball were hollow except for a small, very dense sphere rigidly fixed to a spot inside the spherical surface. --Dan _____________________________________________________________________ "It don't mean a thing if it ain't got that certain je ne sais quoi." --Peter Schickele