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Relative potential energy

  1. Nov 17, 2012 #1
    1. The problem statement, all variables and given/known data
    A creane lifts a 1500 kg car straight 20 m [up]
    How much potential energy does the car gain?
    How much energy does the crane transfer to the car?
    How much work does the crane do?



    3. The attempt at a solution
    How much potential energy does the car gain?
    Eg = mgh
    Eg = (1500 kg)(9.8m/s^2)(20m)
    Eg = 294000 J

    How much energy does the crane transfer to the car?
    Eg = - 294000 J

    How much work does the crane do?
    I am not sure
     
  2. jcsd
  3. Nov 17, 2012 #2

    haruspex

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    If A were to transfer a negative amount of energy to B, would that not be the same as taking energy from B?
    In the absence of any data concerning losses due to friction etc., what do you think the answer is?
     
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