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Perpetuum mobile

  1. Apr 12, 2006 #1
    some people say you can't have more energy output from a system than you put in it since it violates second law of thermodynamics.

    doesn't it violate the same law when one drops an a-bomb on the ground? don't you get much much more energy than the one you could get only from the kinetic energy the bomb has while it touches the ground?

    please, explain me that paradox with 2 thing in the mind:

    1) no reference shoud be made to any type of stored of whatever type of (say nuclear) energy; the same argument could be applied to any system, since it might be possible to derive a lot of energy from a given system after somehow disturbing it and releasing certain type of stored energy. by the way, releasing much mooooooore energy than was transfered to that system. after all how much do we know about nature?

    2) no mathematics shoud be employd to prove otherwise. math and logic does not have to do anything with how the nature operates. it's probably good for quantitavie description of a physical process.
  2. jcsd
  3. Apr 12, 2006 #2
    I think you must also take into consideration what kind of energy you are using ultimately.
    In the a-bomb you use nuclear energy which is harnessed through nuclear chain reactions.The energy was already present in the nucleus.
    Similarly when you use electricity at home, the only work that you
    do is plug the appliance on and voila you have energy.We don't have to wonder how we happen to get more energy (through the power generators of course).So no violation of 2nd law.
    It does matter to take into account what agencies work to harness any form of energy (including nuclear) and so 2nd law of thermodynamics always holds good.
    Last edited: Apr 12, 2006
  4. Apr 12, 2006 #3


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    This has got to be THE silliest set of requirements I've ever seen. By YOUR definition, fusion is a "perpetuum mobile". And according to your criteria, science is sufficiently done by saying "everything that goes up, must come down" without caring when and where it comes down.

    This isn't science, and your irratonal made-up criteria is doom to fail. This thread is done.

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