(Solved): The quadriceps muscle is exercised isometrically with the knee flexed at 50 degrees. At the ankle, ...

The quadriceps muscle is exercised isometrically with the knee flexed at 50 degrees. At the ankle, \( 0.6 \mathrm{~m} \) from the center of motion of the knee, an external force of \( 200 \mathrm{~N} \) is applied perpendicular to the long axis of the tibia. The moment arm of the patellar tendon force is \( 0.07 \mathrm{~m} \). The force transmitted through the patellar tendon acts at an angle of 20 degrees to the long axis of the tibia. The tibial plateau is perpendicular to this long axis. The weight of the lower leg may be disregarded. How large a force in Netwons must the patellar tendon exert for the lower leg to remain in 50 degrees of flexion?