Native
Free Natural Philosopher & Comparative Mythologist
All over in cosmos there is no objects moving in a "straight line", since all objects have a "angular momentum" - (thanks for your correction).Let's go over this a little bit more just for fun.
Say that the force of gravity suddenly disappeared between the Earth and the Moon. The Moon would go off, but not on a radius, but on a tangent. You forgot the conservation of momentum. It would go in a straight line, starting as a tangent to its orbit at the time that gravity "stopped". You mentioned "orbital momentum", the correct term that you wanted to use is "angular momentum". That would have to be conserved too. But angular momentum is the cross product of the momentum and the radius. The object would not move in a circle since its radius would keep growing larger and larger. The angle between the radius and the momentum would keep getting smaller but since the radius is growing that would make up for it. The angular momentum would be conserved. The magnitude of the angular momentum would be m*v*r*sin(angle between r and v).
For my part "gravity" already has dissapered between the Earth and the Moon, simply for the fact that it never has been there in the first place
You:
"The object would not move in a circle since its radius would keep growing larger and larger".
It still would move in an enlarging circular motion. Or in a spiraling motion, if you will.