Dynamics of two particles on a vertically driven plate

We experimentally investigate the dynamics of two particles driven vertically and free to collide in a nearly one-dimensional channel. Both spherical particles are Delrin with a diameter of d = 5.0 mm . We obtained data for driving frequencies, f , ranging from 26.06 to 29.52 HZ and acceleration magnitudes, Γ, from 1.79 to 2.42 g . High speed digital imaging is used to extract the positions of the two particles from experiment, with digital imaging analysis used to extract velocities and accelerations from sequential images. The total energy and the velocity of the particles before and after collisions are studied in both the lab frame and centre of mass frame. Most of the experimental results suggest a linear dependence for the relative velocity after collision on the relative velocity before collision with the coefficient of restitution approximately constant at 0.8. However, some data in the low impact velocity regime indicates the possibility of an occasional energy transfer between the rotational and translational degrees of freedom.