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Physics V Beam Problem

  1. Nov 28, 2013 #1
    1. The problem statement, all variables and given/known data

    Two identical, uniform beams weighing 260 N each are connected at one end by a frictionless hinge. A light horizontal crossbar attached at the midpoints of the beams maintains an angle of 53.0 ∘ between the beams. The beams are suspended from the ceiling by vertical wires such that they form a "V", as shown in the figure


    What force does the crossbar exert on each beam?


    What is the magnitude of the force that the hinge at point A exerts on each beam?


    What is the direction of the force that the hinge at point A exerts on the right-hand beam?


    What is the direction of the force that the hinge at point A exerts on the left-hand beam?

    2. Relevant equations

    Ʃτ = 0
    ƩF = 0

    3. The attempt at a solution

    I have tried to sum the torques and solve for the force of the bar however I end up getting a fraction with a zero numerator. I don't really know how to "see" this problem even after drawing it.
     

    Attached Files:

  2. jcsd
  3. Nov 28, 2013 #2

    tiny-tim

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    hi djMan! welcome to pf! :smile:
    shouldn't do :confused:

    show us your full calculations :smile:
     
  4. Nov 28, 2013 #3
    Ok,

    Let L = length
    T = tension of each wire
    Fbar = force exerted by bar


    Well what I have so far is:

    Net torque about hinge = Tsin(153.5)L - Fbar * sin(63.5)L/2 - Tsin(153.5)L + L/2*Fbar*sin(63.5) = 0

    And I get a zero each time I try to solve for Fbar
     
  5. Nov 28, 2013 #4
    Hi everyone, I actually found out how to do this problem. Given the fact that everything is in equilibrium I can cut the "V" in half and look at each side using torque. Then I can solve for Fbar without getting a zero for an answer. Lol mastering physics...
     
  6. Nov 29, 2013 #5

    tiny-tim

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    hi djMan! :smile:

    (just got up :zzz:)
    yes …

    as you've probably realised, if you're finding a tension, you have to "cut in half" the thing with the tension before you do your free body diagram, otherwise the tension occurs twice, as a pair of internal forces, which of course add to 0 :wink:
     
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