if perpetual motion is impossible, why/how do planets orbit and spin continually?

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if perpetual motion is impossible, why/how do planets orbit and spin continually?

In: Physics

12 Answers

Anonymous 0 Comments

Perpetual motion is not impossible. Newton states that if there is no force acting on an object its direction and velocity never changes.

As for planets, they got their angular velocity around the sun from the rotating protostellar cloud in which they were “made”.

And their rotation (Spin is used in quantum mechanics) would also be continous if there is no force acting on it. But we have so called tidal locking with the moon. We pull on the moon, thats why we only see one side of it. But the moon also pulls on us, that’s why Earths rotation is slowing down, though very slowly.

Anonymous 0 Comments

The length of time a planet spins is finite, not continuous. They spin due to the gravitational effects of the sun they orbit. The sun has gravitational energy due to its size and the energy inside it. When it runs out, so does it’s effect on the planets. I think.