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Statics: parallel forces problem

  1. Mar 6, 2016 #1
    1. The problem statement, all variables and given/known data

    Determine the x- and y-coordinates of a point through which the resultant of the parallel forces passes.

    3. The attempt at a solution
    The first thing I did was to find the resultant forces, which is R = 0i + 0j -125 k
    Then I found the moment of each axis
    M = (-65(12) -65(6) +60(12) +35(12) ) i + (-65(11)-35(15)+90(15))j + 0k
    M = -30 i + 110 j

    Then the next thing I did is
    r x R = M
    (xi + yj + zk) x (-125 k) = (-30 i +110 j)
    -125y i + 125x j = -30 i + 110 j
    so x and y I got is
    x= 0.24
    y = 0.88

    why is it wrong?
    Thanks for the help

    Attached Files:

  2. jcsd
  3. Mar 7, 2016 #2


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    Did you switch x and y ?
  4. Mar 9, 2016 #3
    Haha I just did and got the right answer. But i don't understand why that's the case. i did all my math right
  5. Mar 10, 2016 #4


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    Says y = 30/125 and x = 110/125 !
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