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Homework Help: Tension required to heal a fractured tibia

  1. Sep 25, 2012 #1
    1. The problem statement, all variables and given/known data
    While a fractured tibia (the larger of the two major lower leg bones in mammals) is healing, it must be held horizontal and kept under some tension so that the bones will heal properly to prevent a permanent limp. One way to do this is to support the leg by using a variation of the Russell traction apparatus. (See the figure) The lower leg (including the foot) of a particular patient weighs 48.5N , all of which must be supported by the traction apparatus.
    What must be the mass of W, shown in the figure?
    What traction force does the apparatus provide along the direction of the leg?


    3. The attempt at a solution
    I have drawn a free body diagram for the weight but other than that I am LOST. It's the only question I have left to do and I've looked over it many time but nothing is clicking. Any help would be greatly appreciated.
  2. jcsd
  3. Sep 25, 2012 #2
    Choosing the weight as your system won't be very helpful. The end result you desire is the value of the weight but choosing it as your system will lead to no useful information in the larger scope of the problem. Can you think of what you know about pulleys and the concentration of forces in the problem to choose the best system?

    BTW: I hope this problem isn't true or I may be permanently limping when I heal up!
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