title: Frictional coupling between sliding and spinning motion.
abstract: The tangential motion at the contact of two solid objects is studied. It consists of a sliding and a spinning degree of freedom (no rolling). We show that the friction force and torque are inherently coupled. As a simple test system, a sliding and spinning disk on a horizontal flat surface is considered. We calculate, and also measure, how the disk slows down and find that it always stops its sliding and spinning motion at the same moment. We discuss the impact of this coupling between friction force and torque on the physics of granular materials.
authors.affiliation: Institute of Physics, University Duisburg-Essen, D-47048 Duisburg, Germany.
authors.forename: Zénó
authors.initials: Z
authors.lastname: Farkas
authors.forename: Guido
authors.initials: G
authors.lastname: Bartels
authors.forename: Tamás
authors.initials: T
authors.lastname: Unger
authors.forename: Dietrich E
authors.initials: DE
authors.lastname: Wolf