2. The model equations
We consider the motion of a solid homogeneous superball of
mass m and radius a, bouncing back and forth under gravity
between a horizontal floor (f) and a vertical wall (w). The motion
is assumed to be two-dimensional, and horizontal and vertical
axes Ox and Oy are taken in the plane of motion of the centre, C, of
the ball such that the horizontal floor is given by y¼ a,
arxo1 and the vertical wall by x¼ a, aryo1. With this
choice of coordinates, the ball centre C is restricted to the positive
quadrant of the plane (see Fig. 1).
Si