  We show that the static friction force which must be overcome to render a
sticking contact sliding is reduced if an external torque is also exerted. As a
test system we study a planar disk lying on horizontal flat surface. We perform
experiments and compare with analytical results to find that the coupling
between static friction force and torque is nontrivial: It is not determined by
the Coulomb friction laws alone, instead it depends on the microscopic details
of friction. Hence, we conclude that the macroscopic experiment presented here
reveals details about the microscopic processes lying behind friction.
