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Homework Help: Simple Truss

  1. Aug 6, 2015 #1
    ImageUploadedByPhysics Forums1438894807.906593.jpg ImageUploadedByPhysics Forums1438894817.790652.jpg


    I am having trouble understanding how the signs were obtained in the moment calculation.

    When I imagine the 600 N force acting on the moment arm, it moves CW which would give it a negative value. When I solve the problem I end up reviving Ay and Cy values that are swapped with the book.
  2. jcsd
  3. Aug 6, 2015 #2


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    The 600N force is to the right, that's counter clockwise about point C.
  4. Aug 6, 2015 #3
    I thought that I'm suppose to draw a line down from C to the line of action of the force. Then apply the force to that line, and imagine (ignore that)

    As I'm writing my response I see that it is CCW. I have no idea why I thought it was CW and was so insistent upon that. Thank you for the reply.
  5. Aug 6, 2015 #4


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    You're welcome :smile:
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