A 3 kg block slides down a 1.2 m long ramp tilted at 20 degrees from horizontal. Without friction, its kinetic energy at the bottom is 12 J (choice d). With a kinetic friction coefficient of 0.15, its kinetic energy is 7 J (choice d). A 3 kg hollow ball rolls down the same ramp without slipping. Its rotational kinetic energy at the bottom is 12 J (choice c).