Leigh is doing a knee extension exercise using a 200 N weight strapped to her ankle 40 cm from her knee joint. She holds her leg so that the horizontal distance from her knee joint to the weight is 30 cm. 10 cm
1. What is the moment arm of the weight about the knee joint axis?
2. For this position, what torque is created by the ankle weight about her knee joint axis?
3. If the moment arm of the knee extensor muscles is 4 cm about the knee joint axis, what amount of force must these muscles produce to hold the leg in the position described? Consider that in addition to the added weight at the ankle, the leg itself weighs 10kg, and the center of mass of the leg (shown by the crosshair circle in the figure) is located at a distance of 10 cm from the knee joint axis.