artificial gravity

[tsukikage]

So... Artificial gravity by rotation only affects objects which are in contact with the surface of the ship, right?
I mean, an object "in the air" would effectively be outside of the system, right?

Comments

[tiwonge.livejournal.com]

Only if it wasn't in contact with the surface when the artificial gravity started. Once it starts, anything that is launched into the air (thrown, dropped, whatever) will have an initial velocity determined by the rotation of the ship. This, and the subsequent rotation, will simulate the acceleration due to gravity.

[tsukikage85.livejournal.com]

So does one get "in synch" with the ship merely by hanging on to a bar on the surface for a couple seconds, or something?

[tiwonge.livejournal.com]

Not really.

Imagine that you're in a moving train. Enclosed in this train, everything's going at the same velocity. So, if you throw a ball up in the air, it doesn't "fall back" to 0 velocity, the same as the ground, right? It behaves normally, relative to that frame of reference.

Now, imagine that the train is constantly accelerating. You'll feel a force pushing against you in the direction of the acceleration. (You'll probably lean forward to try to counteract that force that's pulling you backwards.) The faster the train accelerates, the greater the force is. Now, imagine that the train accelerates at 9.8 m/s^2. This acceleration is equal to the acceleration due to gravity, so the force you feel is equal to the gravitational force. Because of this, you'll be able to walk on the rear wall of the train as if it were the floor. You'll still feel the force of gravity, though.

Now, let's move this train to orbit around earth. (This is really free-fall around earth, which is why it feels like there's no gravity--everything's falling towards earth at the same acceleration.) This train is still accelerating at 9.8 m/s^2, so you'll still feel that force, but there won't be a force due to gravity. Everything else in that train is accelerating with the same acceleration, so it has the same force acting upon it.

How does the train maintain a constant acceleration and not reach the speed of light? It spins in a circle, and the acceleration is the centripetal acceleration (which is equal to v^2/r, where v is the tangential velocity and r is the radius of what is spinning), and is in the direction towards the center. The force you feel, then, will be towards the outside.

So, no. It doesn't get "in synch" with the ship through physical contact. Once it's in the same frame of reference, one stays in that same frame of reference until one leaves it. If you throw something or drop it, it's no longer accelerating, but everything else accelerates to meet it, and it will look the same as if you threw it or dropped it on earth. Well, maybe, in a way. But there's no way it would remain suspended, as if in a 0G environment, because the acceleration of the chamber would move the chamber to meet it--and this would look, like somebody in there, as if the dropped or thrown object had fallen to the floor, instead. In order for it to remain suspended, it would have to accelerate at the same rate as the whole container--it would need some sort of engine to maintain that acceleration.

Does this help?