Rotational dynamics of a driven two dimensional granular array

Video imaging is used to study rotation, and translation in one and two dimensional arrays of cylinders. The cylinders are confined by a block, and pushed along a level track. The position, force and slip events are recorded. In this simple granular system we observe distinct phases of motion depending on the contact forces. This behavior is predicted for the one dimensional case, where the equations of motion can be solved analytically. We discuss how these features relate to the bulk properties of granular media.