Phoenix Business Daily

How does this cup expieriment have to do with inertia?

the expeiriment where you have a cup or a bucket of water, and you swing it upside down, but the water doesn't come out. how does this relate to inertia?

Public Comments

1. Inertia is a property of matter. Centrifugal force, baby. Spin, spin, spin...
2. The inertia of the contents keep them trying to go in a "straight" line. As the bucket curves inward, due to the rope that keeps it in a circular shape, it holds the water to the bottom as the water, in order to go straight, will push toward the bottom of the bucket. The contents trying to continue in a straight line is due to their inertia. Hope this helps. ADDED This same inertia is the reason why, when you let go of the bucket, you can "launch" the bucket and it's contents in a straight line.
3. when you swing the bucket in a circle, the centrifical force of the movement means the water is being pushed against the bottom of the bucket, so it stays in there when the bucket is upside down. It has to do with inertia because the water is being constantly propelled towards the bottom of the bucket, and when the bucket is directly over your head, it remains in the bucket because that centrifical force is more powerful than the force of gravity. For that water to come out, the force of gravity needs to both overcome the force that is pushing the water away from the ground, and then it needs to pull the water back down to earth. Hope this helps. Sometimes its hard to describe physics with the terminology, and examples are best.
4. It depend on the pressure of the air which prevent the water doesn't come out