If something could rotate infinitely after being initially pushed, would the initial push disqualify it from being classed as perpetual motion?

Comments

• Nemo@slrpnk.net ⁨6⁩ ⁨hours⁩ ago

  no, only if it has to be re-pushed periodically

  source
• mvirts@lemmy.world ⁨6⁩ ⁨hours⁩ ago

  Perpetual motion is everywhere in space. Using that motion for doing work will always change the motion, and it will eventually no longer be useful. This is what a perpetual motion machine tries to do but can not.

  source

  • Nomad@infosec.pub ⁨4⁩ ⁨hours⁩ ago

    AFAIK even space will cool down and stop eventually. So not perpetual motion very low friction motion? I know that expansion also plays a role.

    source
• AbouBenAdhem@lemmy.world ⁨6⁩ ⁨hours⁩ ago

  “Perpetual motion” is a bit of a misnomer—it’s only a violation of the second law of thermodynamics if the system is losing energy to friction (or if you try to extract energy from it).

  source
• jeffw@lemmy.world ⁨6⁩ ⁨hours⁩ ago

  This would work perfectly… if we lived in a vacuum

  source
• gedaliyah@lemmy.world ⁨6⁩ ⁨hours⁩ ago

  No, if something rotated infinitely, that still violates thermodynamics and is “perpetual motion.”

  This of course is impossible. Even the Earth slows down by about 2 ms per century due to tidal forces.

  source

  • FuglyDuck@lemmy.world ⁨2⁩ ⁨hours⁩ ago

    “Due to tidal forces”

    Because, the moon (and maybe the sun, and other planets like Jupiter) are acting on it, yeah?

    The earth won’t stop spinning. What’s happening is that the moon’s gravity is slowing the earth’s spin as it drags our oceans towards it.

    Once our day is the same as the moon’s orbital period, then the tide will essentially be fixed, which means it’s no longer slowing us down.

    And all that energy, for the record, is going into the moon and expanding its orbit slightly.

    source