# Q & A: Artificial Gravity

Q:
How does Artificial Gravity work?
- Anonymous (age 12)
Columbia, Missouri, U.S.A
A:

Sir Isaac Newton first came up with the equation for gravity. His equation says that the force of gravity between two objects depends is proportional to the product of their masses and inversely proportional to the square of their separation, https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation. This doesn't help much if we want gravity on a space station, though, since the force of gravity between an astronaut and the space station would be too weak to keep the astronaut from feeling weightless.

One way to make "artificial gravity" would be to design the space station like a wheel and then spin it. If we did this, and we stood on the inside of the wheel, we would feel as though a force were pulling us towards the outer edge of the wheel. This would feel a bit like gravity, but in reality has nothing to do with it.

This works the same way if you take a bucket of water (outside only) and swing it in a big circle. If you swing it fast enough, you can swing it over your head and the water won't come out.

(published on 10/22/2007)

## Follow-Up #1: centrifugal force

Q:
Cosidering the rotation of a bucket holdind in hand and direction of rotation is from down to up, Water will suffer an acceleration towards the HAND and water should fell But it happens vice versa Why ???
- Masood (age 13)
kuwait
A:
It's true that as you swing the bucket the water will be accelerating toward your hand. Something must supply the force to cause that acceleration. There are basically two forces acting on the water:
1. gravity, down
2. the force from the bucket walls.

If the water is swinging fast enough, it's accelerating down faster than gravity would cause it to, even right at the top of the swing. So the bucket force on it must also be down. That means it must be pressing up on the bucket. It doesn't fall out.

Mike W.

(published on 04/05/2010)