physics question

Question

A round object rolls without slipping down an incline. As gravitational potential energy is lost, which of the following is gained?

A. Translational kinetic energy only

B. Rotational kinetic energy only

C. Both translational kinetic energy and rotational kinetic energy

D. Neither translational KE nor rotational KE--both stay constant

Answer 1

C. The object will not quite accelerate down the ramp as its mass alone would dictate, since the friction force at the momentary contact point (it is not slipping) has to overcome its inertia to make it rotate (also increasing). so both linear and rotational energy increase (in a ratio determined by the object's ratio of inertia and its mass).