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 12.5 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 ⋅ m 2 , the muscle force is 1450 N , and its effective perpendicular lever arm is 3.45 cm. Find the magnitude of the angular acceleration α of the weight. α = rad / s 2 How much work W is done if the leg rotates through an angle of 20.0 ° with a constant force exerted by the muscle? W =