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Homework Help: Tension on two cables holding a weight

  1. Feb 20, 2010 #1
    1. The problem statement, all variables and given/known data

    A 18.0 kg spotlight is suspended 2.40m below a horizontal pole by two 3.90m long cables that angle upward at equal angles and reach from the top of the light to either end of the horizontal pole.

    2. Relevant equations

    The only equation I have for tension is T=[tex]\mu[/tex]*m*g/(cos[tex]\vartheta[/tex]+[tex]\mu[/tex]sin[tex]\vartheta[/tex])

    3. The attempt at a solution
    My problem is [tex]\mu[/tex] stands for the static friction, which there is none. Do I still need to use this equation or is there a different one I don't know about. Thanks!!
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 20, 2010 #2


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    Homework Helper

    Welcome to PF!
    Tension is just the force that a string or cable pulls with. You need a "free body diagram" showing the 3 forces acting on the load, with angles. Then you write
    "sum of the forces = 0" for the vertical direction (and perhaps for the horizontal direction separately). The tension forces must be separated into their horizontal and vertical components to fit into these equations.
  4. Feb 20, 2010 #3
    Thanks, I was making it way to difficult.
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