Question

Why is it that when water is in a bucket and spinning around in a circular motion and then upside down the water in the bucket does not move or spill? Am not sure on what terms to use to explain why this happens

Answer 1

I assume that you mean the bucket is tied to a rope and the rope is swung in a circular arc, up and down like a ferris wheel.

The bucket and the water are force to undergo centripetal acceleration. If the motion is fast enough, the centripetal acceleration of the water at the top of the arc exceeds gravitational acceleration, and is in the same direction. The walls of the bucket must apply the additional force downwards to enable the circular motion. You can think of it as an additional centrifugal force applied to the water, towards the center of rotation, to keep it in the bucket at all times.