While exercising in a fitness center, a man lies face down on a bench and lifts a weight with one lower leg by contracting the muscles in the back of the upper leg. the weight has mass 13.5 kg, and is 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 1510 n , and its effective perpendicular lever arm is 3.60 cm. find the magnitude of the angular acceleration of the weight.