While exercising in a fitness center, a man lies face down on a bench and lifts a weight with one lower leg by contacting the muscles in the back of the upper leg.

(a) Find the angular acceleration produced given the mass lifted is 10.0 kg at a distance of 28.0 cm from the knee joint, the moment of inertia of the lower leg is 0.900 kg . m², the muscle force is 1500 N, and its effective perpendicular lever arm is 3.00 cm.

(b) How much work is done if the leg rotates through an angle of 20.0° with a constant force exerted by the muscle?