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A Torque question

  1. Jan 2, 2007 #1
    1. The problem statement, all variables and given/known data
    A window washer is standing on a scaffold supported by a vertical rope at each end. The scaffold weighs 185 N and is 3.47 m long. What is the tension in the rope nearest the 747 N window washer when he stands 1 m from one end?

    2. Relevant equations

    sum of torques = zero
    acceleration of gravity equals 9.8 m/s2

    3. The attempt at a solution

    I thought it was a simple problem but I get the answer wrong. My answer is 681.27 N. Is that right? If not how do i get the right answer??:eek:
  2. jcsd
  3. Jan 2, 2007 #2
    The first thing you need to do is to find an appropriate axis and put down all the torque effecting that point both clockwise and counterclockwise. Remember that the scaffold exerts its from the center of its mass.
  4. Jan 2, 2007 #3
    I thought I did that. Is this the right set up?
    0+185N(sin-90)(-1.735m) + 747N(sin-90)(-2.735)-3.47T=0
  5. Jan 3, 2007 #4


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    Staff Emeritus
    Science Advisor
    Gold Member

    Here is your problem. Rewriting what you have written we have;

    [tex] {\color{red}-}(185\times1.735){\color{red}-}(747\times2.735){\color{red}-}(3.47\times T)=0[/tex]

    This would mean that all the torques would tend to rotate the scaffold in the same direction, is the really what is happening?
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