  We present a study of the chaotic behavior of the bouncing ball billiard. The
work is realised on the purpose of finding at least certain causes of
separation of the neighbouring trajectories. Having in view the geometrical
construction of the system, we report a clear origin of chaoticity of the
bouncing ball billiard. By this we claim that in case when the floor is made of
arc of circles - in a certain interval of frequencies - a lower bound for the
maximal Ljapunov can be evaluated by sem-ianalitical techniques.
