A block and sphere are connected by a cord that passes over a pulley as shown. Neglect friction and assume the cord is massless. Take m1 = 2.00 kg, m2 = 5.35 kg, and = 51.0°. If the incline under m2 is rough, what is the minimum value of the coefficient of static friction s for which the system will not move?

I got A, B, and C but I can't get D

Two masses are connected by a rope that hangs over a pulley as shown below. the pulley is a uniform cylinder of radius 푅=0.381meters and mass 푀=3.1푘푔. initially 푚"is on the ground and 푚#rests 2.5 meters above the ground. if the system is released, use conservation of energy to determine the speed of 푚#just before it strikes the ground. assume the pulley bearing is frictionless.