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Homework Help: Find tension and angle

  1. Apr 21, 2012 #1
    1. The problem statement, all variables and given/known data
    A child's indoor swing consists of a rope of length L anchored to the ceiling, with a seat at the lower end. The total mass of the child and seat is m. They swing in a horizontal circle with constant speed v. As they swing around, the rope makes a constant angle θ with the vertical. Assuming the time τ for one revolution (i.e., the period) is known, find the tension T in the rope and the angle θ.

    2. Relevant equations
    Sorry i know this is a long worded problem but can anyone give me a hand getting started with this one? It's centripetal acceleration problem right?

    3. The attempt at a solution
  2. jcsd
  3. Apr 21, 2012 #2


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    welcome to pf!

    hi bcd201115! welcome to pf! :smile:

    do F = ma twice, once for horizontal and once for vertical …

    what do you get? :smile:
  4. Apr 21, 2012 #3
    but how does that help me get the tension in the rope?
  5. Apr 21, 2012 #4
    The tension keep the child from falling to the ground AND keep her swing in a circle.
  6. Apr 22, 2012 #5


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    the tension T and the angle θ are both in both equations,

    so you have two equations with two unknowns … which you can solve!

    show us what you get :smile:
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