Originally Posted by Kage
Kewl, yeah, that'd be one way of simulating it i guess, but I guess that'd use alot of energy? Though in space, you'd need one push, and it'd keep going theroretically.
Though how fast would it have to be spinning?
Thats not how the earth creates gravity is it? by spinning around? Or is it?
Have they ever tried to simulate gravity then in space?
Earth's gravity is created by the size of the planet. The spinning of the planet is actually making us want to fly off, but the gravity keeps us on the ground. Every physical object possesses gravity. That's right, your laundry basket wants to cling to you right now. It's dependent on mass, though. Since Earth is so massive, it has a lot of gravity. The moon has a lot of gravity, too, but it's only about one-eighth of Earth's since it's so much smaller.
Now in the situation I described, there is a centripetal acceleration that always points toward the center of rotation. Your momentum keeps you on the outside walls, though. Some people call this centrifugal force, but it's not a real force - it's just your momentum. Think Newton's first law: Any object in motion stays in motion, and any object at rest stays at rest. This holds true if no forces act on the object. So what's happening is your body wants to travel in a straight line tangential to the rotation, but the wall is a force that holds you in as it rotates.
As for how fast it would have to spin, that depends on how much gravity you want. The faster it spins, the faster your body wants to fly off tangentially which, in turn, simulates a greater acceleration. Here's a little math, I hope it isn't too confusing:
a = (v^2)/r
Where a is centripetal acceleration, v is velocity, and r is radius. Remember, centripetal acceleration always points toward the center of rotation. The centripetal acceleration is being created by the outer wall pushing on you, so this centripetal acceleration would be the perceived "gravity."
So let's assume the radius of the spindle that is rotating is 100m. If you want to simulate Earth's gravity, just plug in the numbers. (Earth's gravity is scientifically accepted to be ~9.81 m/s^2, but this number varies depending on where on Earth you are and your altitude, among other things. For this calculation, I will use 9.81 m/s^2.) Plugging in the numbers, you get
v = sqrt(a*r) = sqrt(9.81*100) = 31.32m/s
So, to simulate Earth's gravity on this particular spindle, it would have to spin at 112.75km/hr or 70.06mi/hr. Keep in mind that this velocity is the tangential velocity. The radial velocity would be 0.3132rad/s at the greatest radius (tangential velocity divided by the radius which gives the radial velocity in radians per second). The difference between tangential velocity and radial velocity is that tangential is the velocity of a point if it were to keep going in a straight line. Radial velocity measures how many radians a point traverses in a certain time. (Radians are like degrees of a circle, just a different unit.)
Sorry for the physics lesson, I just find this sort if stuff quite interesting. Anyway, I'm not sure if they've actually tried this, but I don't think so.