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Homework Help: Equlibrium and Gravitational Force

  1. Nov 11, 2009 #1
    1. The problem statement, all variables and given/known data

    In the figure below, a uniform beam of length 12.0 m is supported by a horizontal cable and a hinge at angle θ = 70°. The tension in the cable is 500 N.
    (a) What is the gravitational force on the beam, in unit-vector notation?

    (b) What is the force on the beam from the hinge, in unit-vector notation?


    2. Relevant equations
    Torque = r x f

    3. The attempt at a solution
    The system is in equilibrium and so I assumed that the two should be the opposites of each other. My real problem, however is I have no idea how to calculate the Torque or the gravitational force without knowing the weight on the beam.
  2. jcsd
  3. Nov 11, 2009 #2


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    Science Advisor
    Homework Helper
    Gold Member

    not true, sum moments to get reaction force
    But you are given the tension in the cable.
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