Finding the force of the femur on the knee cap.

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SUMMARY

The discussion focuses on calculating the force exerted by the femur on the kneecap using a simplified model of the leg. Given a force from the quadriceps muscle of 420 N, the x and y components of the femur's force were determined to be 191.4 N and -1.67 N, respectively. The angles of the tendon with respect to the vertical were θ1 = 23° and θ2 = 24°. The calculations utilized the equations of motion, specifically fnet = ma, to solve for the forces acting on the system.

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Homework Statement



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 = 420 N, what is the force of the femur on the kneecap? 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 modeled by a rope and the kneecap acts like a pulley. The tendon above the kneecap makes an angle θ1 = 23° with respect to the vertical, and the portion of the tendon below the kneecap makes an angle of θ2 = 24° with respect to the vertical. Enter the x component, followed by the y component.

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Homework Equations



fnet=ma



The Attempt at a Solution



I tried:

Fnetx=max
T1x + T2x + Ffemurx = 0
-240sin23 + -240sin24 + Ffemurx= 0
-93.78 -97.62 + Ffemurx=0
Ffemurx= 191.4N

Fnety=may
T1y + T2y + Ffemury=0
240cos23 -240cos24 + Ffemury=0
220.92-219.25 + Ffemury=0
Ffemury=-1.67N
 
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I see only very small picture. Can not you show a bigger one? ehild
 

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Calculating force of the femur on the knee cap.
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