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Torque problems-gravity

  1. Jul 12, 2013 #1

    I was working on a problem dealing with torque, and it was basically a long piece of wood resting on top of two metal poles. (scaffold like), and a worker standing on one end of the wood.

    When i was reading the solution, i noticed that gravity was factored in at the center of mass.
    I think this is because I chose the pivot point as the intersection of one of the metal poles and the piece of wood.

    My question is: is gravity in torque questions ALWAYS factored in at the center of mass??

    Thanks a lot!!
  2. jcsd
  3. Jul 12, 2013 #2


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    hello oneplusone! :smile:
    yes …

    the total gravitational force on a body is always through the centre of gravity (that's for all purposes, not just for torque) …

    that's the definition of centre of gravity​

    we always assume that any apparatus on earth is in a uniform gravitational field,

    and in a uniform gravitational field, the centre of gravity and the centre of mass are the same (for fairly obvious reasons) :wink:
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