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DY: Fachverband Dynamik und Statistische Physik
DY 40: Posters II
DY 40.19: Poster
Thursday, March 17, 2011, 17:00–19:00, P3
Football in the rain - Rebound of balls from wetted ground — •Frank Gollwitzer1, Kai Huang1, Ingo Rehberg1, and Christof A. Krülle1,2 — 1Experimentalphysik V, Universität Bayreuth, D-95440 Bayreuth, Germany — 2Maschinenbau und Mechatronik, Hochschule Karlsruhe - Technik und Wirtschaft, D-76133 Karlsruhe, Germany
Considering the loss of energy when a solid particle hits hard on a flat surface and rebounds back into the air dates back to I. Newton who defined the coefficient of restitution for this inelastic collision as the ratio of the rebound vs. the impact velocity. Since the theoretical treatment of this complex phenomenon is difficult, experimental data are needed for comparison with elastomechanical models. It is known that the restitution coefficient depends on various parameters like impact velocity, size of the balls, materials involved, etc. Here we present results of an experimental investigation of the multiple collisions of a solid sphere hitting a hard surface wetted with liquid of various properties. For example, it is observed that the rebound occurs only above a critical approach velocity. From this, the energy needed to break the capillary bridge between ball and ground can be deduced.