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Homework Help: What is the efficiency of the engine?

  1. May 14, 2006 #1
    f an engine must do 500 joules of work to pull a 10 kg load up to a height of 4 meters, what is the efficiency of the engine?

    So that's

    which gives me 0.008

    Does that mean the efficiency is 8%?
  2. jcsd
  3. May 14, 2006 #2
    where did you get your numbers from?



    None of this makes any sense.
  4. May 14, 2006 #3
    Work done: 10kg*9.8N/kg*4=appx 400J

    efficience= work done/500 * 100
  5. May 14, 2006 #4
    400J is not correct, please write down the correct numerical value.

    Your second line is not correct.

    efficiency = work needed ideal/ work actually required

    It is always less than one.
  6. May 14, 2006 #5
    Okay for my first line, I got 24.5

    and I don't know how I'm messing up on my second line. ??
  7. May 14, 2006 #6
    where are you getting these number from?

    You need to start showing me your work and not just some random numbers you are calling approximations.
  8. May 14, 2006 #7


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    Bluemoon : Please write down the equations before plugging in numbers.
    Last edited: May 14, 2006
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