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Equilibrium practice final exam problem

  1. Dec 12, 2009 #1
    1. The problem statement, all variables and given/known data

    A 17.674 kg 2.0m long horizontal uniform beam is hinged at one end and it is supported at the other end by a cable that makes an angle of 60 degrees to the horizontal.

    Calculate the tension in the cable when it has been shortened so that the beam makes an angle of 60 degrees to the horizontal.

    2. Relevant equations

    [tex]\sum F_{x}=0[/tex]

    [tex]\sum F_{y}=0[/tex]

    [tex]\sum \tau=0[/tex]

    3. The attempt at a solution

    After finding the equations using [tex]\sum F_{x}=0[/tex] and

    [tex]\sum F_{y}=0[/tex], I realized that we only need that [tex]\sum \tau=0[/tex].

    So working with that, I got

    [tex]\sum \tau=0 \Rightarrow \1cos60*17.674*9.81-Tsin120*2=0 [/tex]

    Solving for T would give T = 50.05 but the answer booklet says its 5.10. Any help would be appreciated. Thanks!
  2. jcsd
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