Experimental determination of the coefficient of restitution for meter-scale granite spheres

We present results of a series of large-scale experiments to measure the coefficient of restitution for 1-m-diameter rocky bodies in impacts with collision speeds up to similar to 1.5 m s(-1). The experiments were conducted in an outdoor setting, with two 40-ton cranes used to suspend the similar to 1300-kg granite spheres pendulum-style in mutual contact at the bottoms of their respective paths of motion. The spheres were displaced up to similar to 1 m from their rest positions and allowed to impact each other in normal-incidence collisions at relative speeds up to similar to 1.5 m s(-1). Video data from 66 normal-incidence impacts suggest a value for the coefficient of restitution of 0.83 +/- 0.06 for collisions between similar to 1-m-scale spheres at speeds of order 1 m s(-1). No clear trend of coefficient of restitution with impact speed is discernable in the data. (C) 2010 Elsevier Inc. All rights reserved.