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Signing UpStep 1: Materials and Tools
Materials
- 1/4'' Copper Tubing $6.48 for 5 feet at Lowes. Make sure it is pliable.
- Caulk/Sealant $1.28 at Lowes. Food safe caulk would work the best.
- Water bottle- You can find these in the trash.
- Drill with a 1/8 in. drill bit
- Hacksaw to cut the copper tubing
- Measuring device











































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or bubble gum. seriously. mash it in. it'll last a frighteningly long time.
or a cork (from wine, for example)
khouse6@dtccom.net
As water is removed from the bottle by the birds, a vacuum is created inside the bottle. Nature* abhors vacuums** apparently and tries to fill it in - this is air pressure: at sea level this is about 101.3 kPa or 14.7 psi (see Wikipedia for "Atmospheric Pressure"). Because the bottle's pipe is pointing down, the two forces of gravity and air pressure oppose each other, with air pressure winning until additional force is applied by capillary action*** or birds sucking (an opposing vacuum).
The pipe diameter makes a difference: roughly speaking, a wide pipe means that the air pressure is spread over a greater area (so for a square-inch-area-sized pipe the pressure is 14.7 pounds and for a quarter-square-inch-area-sized pipe the pressure will be four times the amount: 58.8 pounds****). The bend in Brennn10's pipe is helping because it is restricting the area of the pipe.
If the bottle is not rigid enough, the sides will collapse, reducing the volume - and therefore the vacuum - in the bottle, allowing gravity to win for a bit.
* ...and teenagers and some adults, if their rooms are anything to go by.
**...the only reason we have an atmosphere is because the same "thing that keeps us from floating off of the earth" is also stopping our air flying off into the vacuum of space. Good design, that.
*** ...like when you touch the end of the pipe and water flows over your fingers until the increased vacuum in the bottle overrides it.
**** ...or thereabouts, but you get the idea.