(2) Faculty of Natural Sciences and Mathematics, P.O.Box 162, Skopje 1000, Macedonia

We study numerically the motion of a classical particle in a homogeneous gravitational field bouncing elastically from a boundary limiting the motion from below. The boundary is piecewise linear and has wedge-like shape which is periodically extended over the entire horizontal axis. The angle characterizing the symmetric wedge discriminates between the region with only chaotic motion, and the region with periodic, limited or extended quasiperiodic, and chaotic trajectories.

It is observed that for a random set of initial conditions on the constant energy surface, the mean-square displacement asymptotically becomes linear function of time. The diffusion coefficient is examined as a function of energy and wedge angle. For large wedge angles and intermediate values of time t, the mean-square displacement scales as a power function of time with degree which can be larger then 2.

Examination of higher order moments gives further numerical evidence for tendency toward Gaussian distribution.