Odd Question, kind of physics related

Originally posted by AThousandYoung
But what if you bump it?

It has been suggested that gravity will naturally correct bumps.

It does not work for the real earth due to reasons already mentioned here by other folks:
The earth is not spherical, the gravity is not uniform, there are bumps(mountains and valleys), other forces acting on the ring such as wind, etc, etc..
HOWEVER, if the ring's diameter is not just slightlty greater than earth's (as in the original hyphotesis), but much greater, then the effects of these irregularities become more and more negligible as the ring's diamater increases. But as you minimize the problem of irregularities as you move the ring away from earth, the asymetrical gravitational pull of the moon would prevent the ring from staying concentric. You would need to assume the earth "moonless". But again, not the real world.

Originally posted by Feastboy
Is the earths center of gravity always in the center? I know the magnetic poles shift but would the movement of rock under the earths crust continually alter the earths center of gravity slightly?

Also you'd have to take into account the moons gravity, I'm presuming if it can effect water it might be able to effect a giant planetary ring. Or would this effect be negligible?

Actually, moons effect is dramatic, the center of gravity of the the two bodies as one system is what you'd be orbitting around, in fact you'd also probably have to take itno account the sun too, but for the purposes fo the original hypothetical satelite ring, simply look at the centers of gravity like point masses, once the centers of gravity for the two bodies are overlapping, bob's your uncle.

Originally posted by agryson
Actually, moons effect is dramatic, the center of gravity of the the two bodies as one system is what you'd be orbitting around, in fact you'd also probably have to take itno account the sun too, but for the purposes fo the original hypothetical satelite ring, simply look at the centers of gravity like point masses, once the centers of gravity for the two bodies are overlapping, bob's your uncle.

Correct. The sun too must be taken into account.