1. Introduction
In a previous paper [1] two of the present authors considered in detail the mechanics of a superball bouncing back and forth on a rough horizontal plane. Reversals in direction in the horizontal motion of the ball result from the application of a tangential law of restitution at the point of impact of the ball and the plane. This concept was first introduced by Garwin [2] who used a tangential coefficient of restitution of one, which is not physically realistic. Garwin’s model was modified by Cross [3] who employed a tangential coefficient of restitution a satisfying 0 o a o 1, with the horizontal velocity of the point of impact of the ball being reversed and reduced in magnitude by a factor of a in the impact. Further details of the physics of this model are given in [1], together with references to other theoretical and experimental work.
All who have experimented with a superball will have at sometime bounced the ball on the floor, followed by a bounce on a vertical wall. If the bounce on the wall occurs while the ball is still rising, it gives the ball some backspin, so that the direction of motion is reversed at the next bounce on the floor resulting in the ball hitting the wall a second time. With practice, the ball can be made to bounce between the floor and wall several times. Such motion is illustrated in the animations in Figs. 2, 3, 5, and 11. It is our purpose to give a theoretical investigation of such motions and the non-linear mappings which they engender. To this end we establish in Section 2 the basic equations governing the model.