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Homework Help: Efficiency Question

  1. Dec 1, 2009 #1
    1. The problem statement, all variables and given/known data

    A engine used to raise a lift is 60% efficient, and the lift's mass is 2000kg. How much energy would be needed to raise it to 10m?

    2. Relevant equations

    Efficiency = energy output/ energy input *100

    3. The attempt at a solution

    EP=mgh = 2000*9.8*10= 196000 J.

    Therefore, eff. = energy output/energy input *100 = (0.6=EOUT/196000

    EOUT= 0.6*196000=117600 J

    Am I on the right track?
  2. jcsd
  3. Dec 2, 2009 #2


    User Avatar
    Homework Helper

    Hi kabton14, welcome to PF.
    Here Eout = mgh.
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