Given no external influences that is actually just normal behavior. In a vaccum away from any gravitational influence or such once you push something it should keep going. Thats conservation of momentum. Air resistance and such is why things stop.
no, only if it has to be re-pushed periodically
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.
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.
If you think about it, when the universe cools down, maybe some rocks will fly forever without hitting anything.
A cooled down universe does not move at all AFAIK. please Look up Brownian motion.
If a rock is moving between galaxies, what would make it stop?
Does a given mass ever get outside the influence of both galaxy’s gravity influences?
“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).
If something could move forever, without further input of energy, then yes, that’s perpetual motion. We just haven’t found anything which will do that yet and out best models for describing the universe hold that it’s impossible.
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.
“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.
Yes, although quantum effects also slow spinning celestial objects/systems, even in the absence of measurable tidal effects. That would take much, much longer to slow down.
What quantum effects exactly? How does that work?
I’m not a scientist so I don’t claim to understand it or explain it.
Ah, thanks. Thats explains it quite good. Basically everywhere in space we have at least some energy. And where we have enery particles will pop into existance and be destroyed again (photons mostly I guess for low energy like with the background radiation in space). These particles only live a short amount of time, but they can still collide with objects like dust or even planets. And when these objects move, the particles in the front will basically collide harder/more, than in the back. Thus a small force against the moving direction is exerted on the object, proportional to its speed (just like friction). Though this is only significant for small objects like dust or on a very very very long time scale.
This would work perfectly… if we lived in a vacuum with no gravity or other forces acting on the object
