For 10 points, name this force which opposes sliding motion between two surfaces.
When this is present in a harmonic oscillator damping can occur, while approximations used to model it assume that it is independent of contact area. On the molecular scale, this phenomenon is caused by deformation of irregularities in surfaces and subsequent heat loss. This force allows a wheel to roll without slipping and has a model named for Coulomb. That model for this force states that for a body at rest it is less than or equal to the normal force times a namesake coefficient, and it has static and kinetic varieties. For 10 points, name this force which opposes sliding motion between two surfaces.
When this is present in a harmonic oscillator damping can occur, while approximations used to model it assume that it is independent of contact area.
{frictional} force