From: Loser, posted to M.A. Comments board:
you guys have no information on how water finds its own level PLEASE GET SOME IT'S FOR MY SCIENCE EXPERIMENT
Googling has now officially replaced thinking. A student is simply the passive device through which a teacher's question is transmitted to the Internet, where an answer magically appears. And heck, I didn't do my own homework in school. Not going to start now doing other people's. But thank you for asking and for saying "please" to a disembodied etherbeing who doesn't even have the power to send you to your room without dessert for not saying "please."
So, okay, you want your basic physics experiment that will be eye-catching yet scientifically relevant. For that you'll need a garden hose, a clarinet, a big cannoli shell (unstuffed), a five-inch PVC sewer pipe, ziti (uncooked, no sauce), a megaphone, bagpipes, a flute, and a large glass globe with a hole in the top and bottom. Stretch the garden hose straight and horizontal, close off the ends, and punch enough holes in it to stick each of the other objects into it perpendicularly -- so water will flow through the hose and in and out of the bottom of the bagpipes, the ziti, etc. Now take a big bunch of water and pour it into, oh, maybe, the glass globe. It doesn't really matter. Start with the clarinet, if that suits you. After you've poured in what you figure is "enough" water, stand back and look at your experimental array. Take our word for it (since I guess you can't really see the water level in any but the glass), the water in each of the things stuck in the garden hose is at the same level as in each of the others. Straight as an arrow, an equal distance above the garden hose. The water's no higher in the sewer pipe than it is in the cannoli. Water has sought its own level and you've proved it. This works because gravity never sleeps, and because no matter the size or shape of the thing sticking out of the garden hose, the pressure of the water at any given point on the side of the thing will remain equal. Pour more water into the clarinet, and the level will change in all other things to come back into balance. You've also just shown that water will flow uphill inside a bagpipe if conditions are right.