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Statics : Direction of Moments

  1. Oct 9, 2015 #1
    I still don't really get the concept of moments..

    if moment is what makes things rotate, imagine this :

    ....................................... F (pushing down the stick)

    so :
    1. the stick will rotate in a clockwise direction,
    2. but the direction of the moment is negative Z.. (right hand rule)
    I just don't get the correlation between the two !
    my mind : The stick will rotate in a clockwise direction, and has nothing to do with the Z axis..

    Anyone.. ?
  2. jcsd
  3. Oct 9, 2015 #2


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    Science Advisor

    Which way does the angular velocity vector point, when it rotates in a clockwise direction?
  4. Oct 9, 2015 #3
    It depends on how you choose your coordinate system. If you choose the x axis along the stick, and the y axis vertically up on the page, then the z axis is out of the page for a right handed coordinate system. Once you fix your axes like that, a clockwise moment is described by a vector which points in the negative z direction.
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