Ryan is doing leg curls on a Cybex machine. He gets stuck with 90 degree angle at the knee joint. The force exerted by the machines(FA), on his leg is 600N, directed at an angle of 55 degrees relative to the tibia, and the distance from Ryan's knee joint to the point where the force is being applied is 55 cm (distance L). For this problem, assume the weight of the shank and foot is negligible and the muscle force (FM) acts perpendicular to the tibia in this position.
a. What is the length of the moment arm from the knee joint to the applied force?
b. What is the torque created by the applied force (FA), about the knee joint?
c. After finding the troque above, how much force is required from the hamstrings (FM) to balance or offset the extension torque created by the applied force(FA)?