A wheel free to rotate about its axis that is not frictionless is initially at rest. A constant external torque of +50 N·m is applied to the wheel for 21 s, giving the wheel an angular velocity of +650 rev/min. The external torque is then removed, and the wheel comes to rest 120 s later. (Include the sign in your answers.)
(a) Find the moment of inertia of the wheel.
(b) Find the frictional torque, which is assumed to be constant.