A 6-in.-radius pulley of weight 5 lb is attached to a 1.5-in.-radius shaft that fits loose...

A 6-in.-radius pulley of weight 5 lb is attached to a 1.5-in.-radius shaft that fits loosely in a fixed bearing. It is observed that the pulley will just start rotating if a 0.5-lb weight is added to block A. Determine the coefficient of static friction between the shaft and the bearing.