A rigorous analysis of the bounce of a ball is complicated
by several factors, one being that in practice, a relatively soft
ball can easily squash to half its original diameter and also
squash asymmetrically, in which case the relation between
the compression of the ball and the displacement of its center
of mass is not easily determined. Another complicating factor
is that the ball compression versus the applied force relationship
is not only nonlinear but may also vary with frequency,
in which case a static force versus compression
curve is not particularly relevant, and dynamic curves for a
spherical object are not readily available, if at all