The diagram of the leg shows the femur (1) and tibia (2). The quadriceps muscle
ID: 1340278 • Letter: T
Question
The diagram of the leg shows the femur (1) and tibia (2). The quadriceps muscle (3) applies a force to the lower leg via a tendon (4) that is embedded with the kneecap (5). If the force applied by the muscle to the tendon is FM = 660 N, what is the force of the femur on the kneecap, if the leg is in equilibrium? A simplified model of the leg is shown next to the diagram. The leg bones are represented by two beams attached by a pin. The tendon is modelled by a rope and the kneecap acts like a pulley. The tendon above the kneecap makes an angle ?1 = 68° with respect to the vertical, and the portion of the tendon below the kneecap makes an angle of ?2 = 29° with respect to the vertical. Enter the x component, followed by the y component.
answer 1 of 2 ______
answer 2 of 2 _______
Explanation / Answer
net force along x direction F femur = -Fm sin 29 + Fm sin 68
Ffemur = -(660 * sin 29) + (660 * sin 68)
Ffemur = - 291.96 N long -ve x axis
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a long y axis
Fm( cos 68 - cos 29)
= 660 * ( cos 68 - cos 29)
= -330 N