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Torque Problem

  1. Dec 17, 2008 #1
    1. The problem statement, all variables and given/known data

    Find net torque.

    2. Relevant equations

    T = F(d) and T = F(d)sinx

    Torque = T
    Force = F
    d = distance

    3. The attempt at a solution

    100(0) - 200(4)sin40 - 120(14) + 150(8) = -994.2 Nm

    Did I do this correctly? Notice I crossed out the 400N also because I think that it does not affect it.
  2. jcsd
  3. Dec 17, 2008 #2


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    Homework Helper

    Welcome to PF.

    I think your second term is 6m from the pivot not 4m.

    Your bottom force - 150N - is 15m from the pivot not 8m as your equation suggests.
  4. Dec 17, 2008 #3
    Ah, thanks, but how is 150N 15m away from the pivot point? Do I just go up? Sorry I do not understand :(
  5. Dec 17, 2008 #4


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    Homework Helper

    It's the projection of the force to a line that is perpendicular to the pivot. That is the way you should be taking Torque.

    For instance the one at an angle of 40° if you extended that out you would see that the lever arm that is perpendicular to the force is Sin40° times the 6m length.

    For the bottom force it is acting horizontally, but it is acting through the vertical line from the pivot at a distance of 14 + 1 = 15.
  6. Dec 17, 2008 #5
    Ahhh...that clears up so many things. Thank you so much!
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