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Homework Help: Water Slide and Energy

  1. Jun 15, 2011 #1
    A 50.8 kg child slides down a water slide with a velocity of 0.9 m/sec at the top. At the bottom of the slide, she is moving horizontally, y=2.5 meters above the water. She splashes into the water d=3 meters to the left of the bottom of the slide.

    a) Assuming potential energy to be zero at the water level, what is the mechanical energy of the child at the top of the slide?

    For this, ME=PE+KE. Since PE=0, ME=0+KE. So ME=0.5 (50.8) (0.9^2), but thats not right.

    b) How high is the top of the slide above the bottom of the slide?
    I dont know how to do this one.
  2. jcsd
  3. Jun 16, 2011 #2
    Mechanical energy is a conserved quantity. Unless things like friction are involved (non conservative forces) but the problem would state this outright.

    Therefore the mechanical energy at the bottom of the slide is the same as the top.

    You are using the KE at the top of the slide plus the PE at the bottom of the slide.. that is not right, you need to add the KE and PE at the same place to find the ME.
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