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Homework Help: Find the moment caused by all the forces

  1. Feb 11, 2010 #1
    1. The problem statement, all variables and given/known data

    two couples are acting on the frame. If the resultant couple is to be zero, find the distance d

    2. Relevant equations

    3. The attempt at a solution
    First find the point, Let's say A on the picture, and find the moment caused by all the forces
    500cos30 x 0.9 acting downward, 500cos30 x (0.9+d) acting upward, moments by 750ns are cancelled, at least that was what i thinking but i dont think this is right method to use..
    is moment by couple = f.d ?
    so d = 1.8m?
    i dont get this........
    Please help me TT

    Attached Files:

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  2. jcsd
  3. Feb 11, 2010 #2


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    Science Advisor
    Homework Helper

    Hi 385sk117! :smile:
    No, you don't need to choose a point …

    the moment of a couple is the same about any point.

    So just use your f.d formula for each couple separately. :wink:
  4. Feb 11, 2010 #3
    Re: couple

    Thankyou :)
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