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While exercising in a fitness center, a man lies face down
Chapter 4, Problem 29PE(choose chapter or problem)
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 20.0º with a constant force exerted by the muscle?
Questions & Answers
QUESTION:
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 20.0º with a constant force exerted by the muscle?
ANSWER:Step-by-step solution Step 1 o f 10 (a) The net torque acting about the knee joint is calculated as, Here, is the net toque acting, is the torque produced due to the weight lifted by the lower leg and is the torque produced due to the normal force acting on the back of upper leg.