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Idea for a perpetual motion machine

  1. Apr 20, 2014 #1
    If someone were to send a probe out to interstellar space, bring it to a full stop and start rotating, would it continue rotating eternally? Or would drag from errant plasma slow it?
  2. jcsd
  3. Apr 20, 2014 #2
    This is a legitimate question. But you should be careful with your words. Perpetual machine questions are banned from these fora.
  4. Apr 20, 2014 #3


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    Staff: Mentor

    This would not be considered a "perpetual motion machine" in the sense that we mean in our rules, anyway, even if it did continue rotating eternally. A "perpetual motion machine" normally means a device that you can extract energy from, perpetually. There's no way to extract energy from this particular device without slowing it down.
  5. Apr 20, 2014 #4
    What if you had the exterior rotating with a stationary generator in the core?
  6. Apr 20, 2014 #5


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    Staff Emeritus
    Science Advisor

    The outside would slow down and the inside would begin to rotate until the two were rotating at the same speed and no more power would be generated.
  7. Apr 20, 2014 #6
    But it would be a way to store energy, though.

    In reality I don't think there is any such thing as a 100% absolute closed system. In this example there would still be gravitational forces, radiation, and interaction with the interstellar medium, even if very small.
  8. Apr 20, 2014 #7


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    Staff: Mentor

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