Sneaky's Daily Did You Know - Baffled With Science

If you swing a bucket of water round and round above your head, the water will stay in it even when the bucket is upside down. The water's inertia tells it to continue rushing through space at a steady speed in a straight line and, having been started in one direction by the swinging bucket, to carry on in that direction. Since the bucket is made to follow a circular path, the water is forced to accelerate to get around the corners. This gives it "artificial gravity" which makes it stick to the bottom of the bucket even when the bucket is upside down.