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Homework Help: Equal moments?

  1. Nov 20, 2013 #1
    1. The problem statement, all variables and given/known data

    Do the following have equal moments about A?



    2. Relevant equations


    3. The attempt at a solution

    Yes because using L*cos(30), they will be the same?

    What is your reasoning?
  2. jcsd
  3. Nov 20, 2013 #2
    Your reasoning is incorrect ...

    τ = r×F

    τ = rFsinθ

    or τ = r times (component of force perpendicular to line joining A and point of application of force )

    So what is τ ?
  4. Nov 20, 2013 #3
    They both use τ = rFsin30 right? That means they are equal! Right?
  5. Nov 20, 2013 #4
    Last edited: Nov 20, 2013
  6. Nov 20, 2013 #5


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    Science Advisor
    Homework Helper
    Gold Member

    "Use" is a strange word there. "Supply" perhaps. Anyway, you asked whether your reasoning was correct, and Tanya S was right in reply, that your reasoning was incorrect (though you got the right answer).
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