3. The pulley in the figure has radius R and moment of inertia I. The rope does not slip over the pulley, and the pulley spins on a frictionless axle. The coefficient of kinetic friction between block A and the tabletop is k. The system is released from rest, and block B descends. Block A has mass mA and block B mass mB. Use energy methods to calculate the speed of block B as a function of the distance d that it has descended. B