A small ball of mass m is aligned above a larger ball of mass M = 0.63 kg (with a slight separation), and the two are dropped simultaneously from a height of h = 1.8 m. (Assume that the radius of each ball is negligible relative to h).
If the larger ball rebounds elastically from the floor and then the small ball rebounds elastically from the larger ball, what value of m results in the larger ball stopping when it collides with the small ball?