A weight lifter is doing a leg extension exercise in a seated position with his knee joint center of rotation fixed on the machine. If his lower leg is at 45 degrees, the angular velocity is 1.5 rad/s and the angular acceleration is 10 rad/s^2. The weights apply a vertical force to his anke joint of 1000 N located 50 cm from the knee joint. Leg mass is 4 kg located 20 cm from the knee and the Icm is 0.25 kgm^2.
a. Determine the total mass moment of inertia for the leg and weights about the knee joint.
b. Determine the knee joint extension moment at this moment in the excercise.