Kinetic Friction due to Ohm ’ s Law Heating

Using both a recent calculation by Bruch of the damping of the motion of a monolayer nitrogen film oscillating harmonically on a metallic surface due to Ohm's law heating and a Thomas-Fermi approximation treatment of the Ohm's law heating mechanism, which accounts for the nonzero thickness of the surface region of a metal, it is argued that this mechanism for friction is able to account for recent measurements of the drop in the friction for a nitrogen film sliding over a lead substrate as it goes below its superconducting transition temperature. Bruch's calculation is also made more transparent by redoing the calculation for a film sliding at constant speed, instead of oscillating. Using this treatment, it is easily shown that Bruch's calculation is equivalent to integrating Boyer's solution of the problem of a charge sliding over a metallic surface over the charge density of the monolayer nitrogen film.