A ball of mass 0.196 kg with a velocity of 1.41 m/s meets a ball of mass 0.302 kg with a velocity of -0.393 m/s in a head-on, elastic collision. (a) Find their velocities after the collision. 1f = m/s 2f = m/s (b) Find the velocity of their center of mass before and after the collision. cm, before = m/s cm, after = m/s