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Conservation of energy Problem

  1. Jan 12, 2012 #1
    A child on a swing pumps hard and achieves a speed of 6.7 m/s at the swing’s lowest point. She then stops pumping. How high above the lowest point does the swing reach after that?

    I honestly have no idea how to go about solving this. I know the velocity is 6.7 m/s (but is it final or initial or both?). I also know gravity is 9.8 m/s. But I don't know anything else?

    I know the equation for conservation of energy is PEf+KEf = PEi+KEi. I know PE= mgh and KE= .5mv2 However, I have no idea how to do this because I don't have the height or the mass, and I don't know if 6.7 m/s is the initial, final, or both. I'm just completely lost.

    Please help! Thanks!
  2. jcsd
  3. Jan 12, 2012 #2
    Never mind I figured it out!
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