Two objects of equal mass and radius—one a solid sphere and the other a thin…
PHYSICS · Single correct · AP · Physics 1: Algebra-based · Energy and Momentum of Rotating Systems · Energy and Momentum of Rotating Systems
Problem
Two objects of equal mass and radius—one a solid sphere and the other a thin hoop—roll without slipping down the same incline. At a point where both have the same center-of-mass speed v, which statement correctly compares their rotational kinetic energies Krot?
(a) The solid sphere has greater Krot because it spins faster than the hoop.
(b) The hoop has greater Krot because its moment of inertia is larger.
(c) Both objects have the same Krot because they have the same mass and center-of-mass speed.
(d) The hoop has less Krot because its larger moment of inertia makes it rotate more slowly.