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Homework Help: Sign Convention of Moments

  1. May 16, 2012 #1
    1. The problem statement, all variables and given/known data

    I have this problem.

    http://bit.ly/JkVdxA [Broken]

    This is a thin-walled cantilever beam subjected to two loads through the shear center. I know how to do all of the calculations, the only thing I am unsure about is the sign convention of the moments caused by the two loads. We are to evaluate the moments at the midpoint of the beam (500mm into the page). I am just a bit unsure about applying the right hand rule to determine the signs of the moments about the axis (which is located at the centroid).


    2. Relevant equations


    N/A

    3. The attempt at a solution

    I think it is
    Mx = -500N * 500mm = -250000Nmm
    My = -300N * 500mm = -150000Nmm

    However I found a similar example that said My was positive. Could someone please explain? Thanks. :)
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
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