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Revolution of planets

  1. Dec 29, 2014 #1
    How do planets continuously rotate on their axis or revolve around stars ? Do the energy they consume for this continued motion gets expelled as heat ?
  2. jcsd
  3. Dec 29, 2014 #2


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    Explain to yourself how they can not.
  4. Dec 29, 2014 #3


    Staff: Mentor

    No energy is consumed for this. A planet in orbit has constant energy: its spin energy is constant, and its orbital kinetic energy changes by the opposite amount that its gravitational potential energy changes.

    Also, if they were consuming energy (which they are not) then they would have to absorb heat (which they do not). Expelling heat would be exactly backwards.
    Last edited: Dec 30, 2014
  5. Dec 30, 2014 #4
    There's no friction, so nothing slows down planets. Gravity do not "consume" any energy
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