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Homework Help: Engineering Statics Equilibrium System Question

  1. Jun 3, 2014 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
    First, I drew the FBD for the system, one horizontal force at A, one force perpendicular to the beam at B, and the weight.
    Writing out the equilibrium equations:
    The sum of forces in the y direction should be 0, so I have the equation:
    Nb cos(θ) - W = 0, which can be rearranged for Nb later on.
    Then I took the moment about point A:
    Nb (a/cosθ) - Wcosθ (L/2) = 0
    Eventually, it simplifies out to cos^-1 ( (2a/L) ^(1/3) ) = θ

    I don't think I got the right answer, but can someone help me identify my error? Thank you in advance.
  2. jcsd
  3. Jun 4, 2014 #2
    Why do you think you have the wrong answer?
  4. Jun 4, 2014 #3
    IDK, it looks just so completely wrong. and also it says that describe it in terms of w, a, and l and I have no w.
  5. Jun 4, 2014 #4
    Would changing W also change θ?

    Also your answer is consistent with the units. If W was in the solution then the units would get screwed up.
  6. Jun 5, 2014 #5
    Hmm, I suppose you're right, thank you for the replies.
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