a solid sphere of mass 1.50 kg is rolling without slipping on a horizontal table with its center of mass moving at 0.50 m/s. the sphere rolls without slipping down a ramp that is 45.0 cm high. (a) what is the speed of the center of mass of the sphere at the bottom of the ramp? (b) what is the rotational kinetic energy of the sphere at the bottom of the ramp?