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Help with pulleys

  1. Sep 18, 2014 #1
    So I have started a conundrum with a question about pulleys. There is one pulley anchored and suspended from a ceiling. There is a 100 pound weight suspended on one pulley and the other end of the rope is anchored to the ground. The question is how much weight is on the pulley? 50 pounds, 100 pounds, or 200 pounds? There is equal force on each end of the rope, so technically there is 100 pounds of force on each side, but does that mean there is 200 pounds on the pulley?

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  2. jcsd
  3. Sep 18, 2014 #2
    By observation there should be 200 pounds of force on the rope holding the pulley (sum of forces in the vertical direction, ignoring angles).
  4. Sep 18, 2014 #3


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    Staff: Mentor

    Yes. And notice that if you were to turn the picture upside down, you'd see how you could lift a 200-lb weight by applying a 100-lb force. This is how a block and tackle works as a lifting aid.
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