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Homework Help: Bicycle coasting up a Hill

  1. Feb 19, 2007 #1
    1. The problem statement, all variables and given/known data

    Coasting along at 7.10 m/s, a 60.0 kg bicyclist on a 7.60 kg bicycle encounters a small hill. If the speed of the bicyclist is 6.00 m/s at the top of the hill, how much work was done on the bicyclist and her bike?


    2. Relevant equations

    KEf-KEi=W
    .5mvi^2-.5mvf^2
    kg*m^2*s^-2
    m=60kg+7.60kg
    v=m/s


    3. The attempt at a solution

    I tried finding the loss in KE and having that be the work done. I get

    .5mVf^2 -.5mVi^2
    .5*67.6kg*36 - .5*67.6kg*50.41

    I get -487 J and it tells me this is the wrong answer? What did I do wrong?
     
    Last edited: Feb 19, 2007
  2. jcsd
  3. Feb 19, 2007 #2

    berkeman

    User Avatar

    Staff: Mentor

    Please write out the whole equations. Include the mass and the units.
     
  4. Feb 19, 2007 #3
    Your final expression is incorrect mathematically.
     
  5. Feb 19, 2007 #4
    I relized i posted that wrong but the answer comes out to -487 the right way but thats the wrong answer. I edited and wrote everything out.
     
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