Question

A solid sphere a solid cylinder, and a hoop each have the same mass and radius. If they are spinning at the same angular velocity, which one has the greatest rotational kinetic energy

Answer 1

KE = 1/2 I * w^2 where I = moment of inertia and w the angular velocity

The hoop has all of it mass at a distance of R from the axis of rotation,

I = M R^2 for the hoop, the others have values of I that are less that of the hoop.