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Equilibrium Style Question involving a Weight

  1. Oct 23, 2009 #1
    1. The problem statement, all variables and given/known data
    While a fractured tibia is healing, it must be kept horizontal and under some tension. One method of doing this is to support the leg by using a variation of the Russel traction apparatus. The lower leg (including the foot) of a patient weighs 51.5N, which must be supported in the traction apparatus. a) What is the mass of the weight shown? b) What traction force does the apparatus apply along the direction of the leg?


    2. Relevant equations
    Newton's second law, pythagorean's theorem, right triangle properties



    3. The attempt at a solution
    No idea where to start with this. The picture of the situation is provided (if it shows up, hopefully). My idea was to find two equations for the traction force and then sub one into the other to solve for the weight. My first equation was tan46=FN/Fapp, where FN=FG leg + Weight and tan37=weight/Fapp. I think this is wrong though because I get an answer that seems too large for the weight, so I have no idea how to properly go about this question. If anyone can be of assistance it would be greatly appreciated, thanks in advance.
     

    Attached Files:

  2. jcsd
  3. Oct 23, 2009 #2

    berkeman

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    Staff: Mentor

    Weird. I approved the attachment, and can see a small thumbnail of it, but when I click on it, I only get a black image with a few words on it. Can anybody else expand the thumbnail?

    Emethyst, can you maybe repost the attachment as a PDF? PrimoPDF is a free writer if you don't have one already.
     
  4. Oct 23, 2009 #3
    Ok does this work for the attachment?
     

    Attached Files:

  5. Oct 23, 2009 #4

    berkeman

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    Staff: Mentor

    I can see it now. I'm not sure, but I think the fact that the two angles are different will give you a net upward force at the leg, which must equal the weight of the leg and foot. That should let you work back to the mass.
     
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