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Homework Help: Pulley system question

  1. Feb 24, 2015 #1
    1. The problem statement, all variables and given/known data
    Hi Guys,

    I am looking at a simple movable pulley system like the one two in from the left. I am trying to work out the relationship between the force applied to the free end (called F2 in the picture) and the tension in the cable

    2. Relevant equations

    3. The attempt at a solution 450px-Four_pulleys.svg.png

    I think that you add the tension in each section of cable so then 2F = T, the tension in the cable is double the force F2 but I'm not sure. Is that correct?

  2. jcsd
  3. Feb 24, 2015 #2


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    But the tension in the cable is given in the figure. F2 equals ____?
  4. Feb 25, 2015 #3
    The tension is 50N so then F = T, as it is for all the options here. Does that mean that F always = T?
  5. Feb 25, 2015 #4


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    "Does that mean that F always = T?"
    What do you mean? What is F? And what is T?
    Depends what F is and what T is. Here FL certainly doesn't equal the tension in the rope.

    When we assume the rope is light and frictionless (which of course it never is!), then the tension in the rope is the same at all points.
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