PHYSICS · Single correct · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion
Problem
A thin hoop and a solid sphere, each of mass M and radius R, roll without slipping across a horizontal surface with the same center-of-mass speed v. Which statement best describes how the rotational portions of their kinetic energies compare?
(a) Both objects have the same rotational kinetic energy because they move with the same speed v.
(b) The thin hoop’s rotational kinetic energy is only slightly greater; the energies are in the ratio 3:2 (hoop : sphere).
(c) The thin hoop’s rotational kinetic energy is greater than that of the solid sphere; specifically, the hoop has 25 times as much rotational kinetic energy as the sphere.
(d) The solid sphere has greater rotational kinetic energy than the thin hoop because its mass is closer to the axis and therefore it can spin faster.