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Homework Help: Moving pulley problem

  1. Feb 5, 2013 #1
    1. The problem statement, all variables and given/known data

    Cable ABC has a length of 5 m. Determine the position x and the tension developed in ABC required for equilibrium of the 100 kg sack. Neglect the size of the pulley

    2. Relevant equations
    TABCosθ + TBCCos[itex]\phi[/itex]=0
    TABSinθ + TBCSin[itex]\phi[/itex]=980N
    I also have the distance from C to the pulley (in x direction) is 3.5-x

    3. The attempt at a solution
    My attempt at the solution so far is
    TABCosθ = TBCCos[itex]\phi[/itex]
    I can rearrange the trig functions themselves, but I'm missing a height component, but I don't even know if that's the right track.
  2. jcsd
  3. Feb 5, 2013 #2
    I have also managed to introduce a few new variables. I have introduced h+H=5 (The length of the rope) and y and y+0.75
  4. Feb 5, 2013 #3


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    Consider the 'free body' diagram for a thin vertical slice of the rope directly under the pulley (thin compared with radius of pulley). What does this tell you about the tension each side?
  5. Oct 28, 2013 #4
    Tension is the same. I tried to find similar triangles and worked with them but I am getting equations with x^4.
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