A 7.600 kg box is resting on a horizontal surface and attached to a 2.400 kg box by a thin, light wire that passes over a frictionless pulley. The coefficient of kinetic friction between the box and the surface is 0.1500. The pulley has the shape of a hollow sphere of mass 1.200 kg and diameter 0.2800 m. The system is released from rest and allowed to move. The hanging box falls 0.6100 m before it hits the ground. What is the speed of the hanging block just before it hits the ground