Experiment 11: Water Pressure vs. Air
This is another experiment that doubles as a magic tric. Amaze your family and friends with this experiment!
1 plastic bottle with a top (it can be a 16 oz-2 liter)
Sharp knife or drill (CAUTION!!)
Sink or bucket
1) have an adult use the sharp knife or drill to make tiny holes along the bottom underside of the bottle. If using a bottle that has 4 little feet (small protrusions) then put one hole in the bottom of each; if your bottle is flat edged n the bottom, then just make 4 equally spaced holes
2) fill the bottle about 3/4 of the way full with water.
3) secret cap on tightly
4) Lift up bottle and be amazed that none of the water leaks out of the holes.
5) holding bottle over sink or bucket tips slightly and watch the water come out of the holes.
Water can only leak out of the holes when air can pass into the bottle via the holes. See inside every object is a constant # of molecules. I an empty bottle the bottle is actually filled with air. If the bottle is filled with water the air is pushed out through the 'mouth' of the bottle. When holding a bottle upright, the air in the bottle goes toward the top the water, toward the bottom. In effect, the water prevents more air from entering the bottle through the small holes - so the water is acting as a plug! When you tip the bottle even slightly, some of the water molecules shifty off of the openings, ever so briefly. This allows some air to enter the bottle and some water to exit the bottle. But it looks like magic to have the water not fall down out of the holes!