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Static equilibrium problem -- with a pulley

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  1. Jul 18, 2015 #1
    1. The problem statement, all variables and given/known data
    20150718_174005_zpspkrqlnql.jpg

    2. Relevant equations
    sum of forces equal to zero.

    3. The attempt at a solution
    20150718_200836_zpsvjmoossd.jpg
     
    Last edited: Jul 18, 2015
  2. jcsd
  3. Jul 18, 2015 #2

    TSny

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    Looks like you left out a moment arm in one of your terms in ΣMA.
     
  4. Jul 18, 2015 #3
    I can't really follow your work computing components of forces and making sure each force contributes to torque.
     
  5. Jul 18, 2015 #4
    Thank you, i didnt notice the 6in on the pulley at first.
    I updated my original post but im still getting the same answer haha.
     
  6. Jul 18, 2015 #5

    TSny

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    Note that FDBsinθ is a force component, not a moment. What's the moment arm for this force?
     
  7. Jul 18, 2015 #6
    oh crap sorry, let me finish that equation.
    Ok, for the sum of moments i got 830.5 lb, now let me correct the rest of the equations and see what i get for an answer to the magnitude of A.
    edit. 880.7 lb
    edit2. 1761.5
     
    Last edited: Jul 18, 2015
  8. Jul 18, 2015 #7

    TSny

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    In the ΣMA equation, your last term is -FDB. Is this meant to be there?
     
  9. Jul 18, 2015 #8
    no its not supposed to be there, ive change it again, ive edited my original post. there is still something wrong with it though...
     
  10. Jul 18, 2015 #9

    TSny

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    Check your calculation of Ax. Looks like you have it set up correctly, but made some sort of mistake in plugging the numbers in your calculator.
     
  11. Jul 18, 2015 #10
    thanks.
    I got a new HP 300s calculator in the mail today, still getting used to it...
     
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