A small coupling is put on a horizontally located rod, which can move along the rod. The rod rotates around a vertical axis with angular velocity W (figure). At the initial moment of time, the clutch is at a distance r0 from the axis of rotation and has a speed v0 directed from the axis of rotation. It further turned out that the coupling speed v relative to the rod increases linearly with distance from the axis of rotation v = v0r/r0. At what coefficient of friction k between the coupling and the rod is such movement possible?

Answer. Format gif