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What is the largest value of Fw the cords can withstand?

  1. Dec 10, 2011 #1
    1. The problem statement, all variables and given/known data

    Cords can withstand a maximum tension of 80N. What is the largest value of Fw they can support?

    2. Relevant equations

    Ft1 and Ft2 are 80.

    FsysX = Ft1 sin 60 + Ft2 sin 70, but x doesn't matter

    Fsys Y = Ft1 cos 60 + Ft2 cos 70 - Fw

    3. The attempt at a solution

    80 cos 60 + 80 cos 70 - Fw
    Fw= 40+ 27
    Fw = 67, when it should be 55.
     

    Attached Files:

  2. jcsd
  3. Dec 10, 2011 #2

    SammyS

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    It's a mistake for you to assume that both F1 and F2 are equal to 80 N. That will lead to a non-equilibrium condition in the x-direction.

    Probably only one of them will be at the maximum value. You should be able to solve for Fw in terms of F1 or F2 .
     
  4. Dec 10, 2011 #3

    So I should say, for example, T1 is going to be equal to 80, solve for T2 in the X direction using that, then use those to solve for the weight.

    I'll try it! Thank you!
     
  5. Dec 10, 2011 #4

    SammyS

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    Yes, you can try that. It may turn out that doing this gives you that T2 > 80 N, in which case you will need to assume that T2 = 80N.
     
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