There are two spheres of the same mass and same radius. one is solid and the other is hollow which of them has a larger moment of inertia about a diameter?

 Answer: The moment of Inertia of a solid sphere= 2/5 mR^2 and that of hollow sphere = 2/3 mR^2 where, m and R are mass and radius of the spheres. This shows That the hollow sphere has a greater moment of inertia than the solid sphere. It is because most of its mass is at a larger distance from the axis of rotation.