A wheel mounted on an axis that is not frictionless is initially at rest. A constant external

Question:

A wheel mounted on an axis that is not frictionless is initially at rest. A constant external torque of 50 N·m is applied to the wheel for 20 s, giving the wheel an angular velocity of 600 rev/min. The external torque is then removed, and the wheel comes to rest 120 s later. Find

(a) The moment of inertia of the wheel, and

(b) The frictional torque, which is assumed to be constant.