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Homework Help: Torque on out stretched arm

  1. Oct 14, 2007 #1
    1. The problem statement, all variables and given/known data
    A 21.5 N weight is held in the outstretched hand of a person with a shoulder-to-elbow length of 33.5 cm and an elbow-to-wrist length of 23.0 cm. The center of the weight is 6.5 cm from the person's wrist. Determine the magnitude of the torque about the elbow produced by the weight.

    2. Relevant equations

    3. The attempt at a solution
    T1 - Elbow
    T2 - Wrist
    T3 - Hand w/weight
    T1D1 + T2(D1+D2) - T3(D1 + D2 + D3) = 0
    T1 = -T2(.565m) + T3(.63)/.335

    I know I am doing something wrong with the torques but I can't figure out what? I thought I just put in 21.5 N.
  2. jcsd
  3. Oct 14, 2007 #2
    I forgot to mention that I put my center of torque at the shoulder
  4. Oct 14, 2007 #3
    Can I not have the center of torque there?
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