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Homework Help: Sledding Energy Question

  1. Jan 12, 2008 #1
    1. The problem statement, all variables and given/known data
    Zeke begins to slide down a snow hill on a rubber mat. Zeke's mass is 76 kg and that of the mat is 2kg.

    2. Relevant equations
    Disregarding frictional forces, how fast are they moving when they are 1.2 m below the crest?

    3. The attempt at a solution
    v=(square root)2gh
    v=(square root)(2)(9.8)(-1.2)
    v=4.85 m/s

    I don't think this is even close to being right, as a friend who I just got done talking to (and is 10x smarter than me) said he got a completely different answer.

    By the way, hello everyone! I just signed up, hoping to learn to understand physics better.
  2. jcsd
  3. Jan 13, 2008 #2

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    Homework Helper

    Hello, we do hope you understand better from now on.

    Does the problem mention 1.2 m vertically below the crest or 1.2 m along the slope?

    If it's the first case, your eqn is correct, except for the minus sign under the sqrt. Is that possible?

    If it's the second case, you'll have to take the component of g along the slope.
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