Bet you can't make water leak out of a hole in abottle!
Get a pair of scissors and a plastic bottle with a screwtop. Make a small hole in the side of the bottle near the bottom with the pointof the scissors. Cover the hole with your finger while you fill the bottle withwater to the brim. (Do this over the sink.) Screw on the top, making sure thereis no air in the bottle. Take your finger away from the hole. Stand back andwatch for the water to come pouring out!
No water? That’s because the odds were stackedagainst it. For water to leak out the hole, the air pressure pushing on thewater has to be less than the force of gravity. Usually the pressure on top ofa liquid is equal to the air pressure pushing on the hole. The two forcescancel each other out; gravity wins and the water rushes forth. (Open the topof the bottle and see this happen.) But as long as the surface of the water isprotected from air pressure by the bottle cap, air pressure works to keep thewater in the bottle. Air pressure then wins because it is stronger than the force of gravity!
You have something else working against youhere, too. It’s the surface tension of the water. It acts like a skin and holdsthe water together. It’s a weak force, but it works for you when you have asmall hole.