Finding the force of the femur on the knee cap.

  • Thread starter Thread starter meaganl
  • Start date Start date
  • Tags Tags
    Force
AI Thread Summary
The discussion focuses on calculating the force exerted by the femur on the kneecap, given a force of 420 N applied by the quadriceps muscle through a tendon. The model simplifies the leg's anatomy, treating the femur and tibia as beams connected by a pin, with the kneecap acting as a pulley. The user attempts to resolve the forces in both x and y components, resulting in a calculated femur force of approximately 191.4 N in the x-direction and -1.67 N in the y-direction. There is also a request for a larger diagram to better visualize the problem. The conversation highlights the complexities of biomechanics in force analysis.
meaganl
Messages
4
Reaction score
0

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.

https://www.physicsforums.com/attachment.php?attachmentid=51494&thumb=1&d=1349314642

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
 
Physics news on Phys.org
I see only very small picture. Can not you show a bigger one? ehild
 

Thread 'Rolling without slipping on a curved surface'

Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
View full post »
Thread 'Voltmeter readings for this circuit with switches'

Thread 'Voltmeter readings for this circuit with switches'

TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
View full post »

Similar threads

Calculating force of the femur on the knee cap.
Replies
1
Views
6K

Hot Threads

Recent Insights

Back
Top