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Sorry but this is another question about PMM.

  1. Apr 29, 2012 #1
    Can perpetual motion machine not produce extra energy just be 100% efficient and still be considered a perpetual motion machine?

    I understand the laws of thermodynamics states that a machine cannot make more energy than it uses. But theoretically if you remove all the losses and have a 100% efficient machine could I call it a PMM or it has to produce more energy to be called a PMM.

    This question is purely whether or not can I call it a PMM.
  2. jcsd
  3. Apr 29, 2012 #2


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    Gold Member

    A PMM (which does not exist) does work. Your hypothetical machine (which ALSO does not exist --- there's no such thing as zero load) does no work so it is not a PMM
  4. Apr 29, 2012 #3
    This doesn't answers my question.

    I know that It doesn't exist and I'm not claiming anything. I do not need people saying "it is impossible" or "does not exist" or "there is no such things". I simply want to know whether or not can I call 100% efficient machine a PMM.
  5. Apr 29, 2012 #4


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    Gold Member

    Since there isn't any such thing, I'm not at all clear that it MATTERS what you call it.

    As I specifically said in my post, a PMM does work and yours doesn't so yours isn't a PMM. Was that not clear?
  6. Apr 29, 2012 #5


    Staff: Mentor

    I think that, by definition, a PMM has to output more work than is input. So a machine that just breaks even is not a PMM.
  7. Apr 29, 2012 #6


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    Staff: Mentor

    See the wiki for pmm: it defines several types.
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