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applied gas laws!

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Corvettaholic:
OK, another great idea.

So lets say you have metal tube just big enough so a steel BB (or plastic) will roll through it easily enough. Maybe a BB coated in oil. So the end of the barrel that isn't the "out" end, you have a nozzle. Aren't compressed air paintball tanks something like 800psi? So if you take the output from that in whatever size tubing it has, and have it go through a nozzle to the little tiny BB barrel. Reduction of 10 in volume results in (ideally) a 10 fold increase in pressure. Boyle's gas laws... applied! In the real world it won't be ideal so maybe you'll only get 5000-6000psi... pushing a BB. Think it'll go through plywood? The better the nozzle, the more likely you are to hit sonic velocities. These kind of nozzles are used for refrigeration systems that go below -100C. They DO let out gas at supersonic velocities. Now a fully automatic multi-barrel version... heehee. Use a rotating disc with a small hole cut out to divert pressure between barrels, and use the pressure itself from the tank to spin the disc, and when the hole reaches any particular barrel air will shoot out and go through nozzle which launches the BB. Pallet shredder?

See... by using gas laws this relates to chemistry!

Corvettaholic:
Need some help with this. I'm also part of a high voltage forum and they're going to help with the electronics part of this, but nobody can agree if the ideal gas law applies here.

A simplified way I'm looking at this. We have a tank of water. Cut a hole in the bottom of the tank, and attach a hose to it with 1" in diameter. The water velocity should be about the same as gravity, right? Lets say at the bottom of this hose, there is a nozzle that is 1/2" in diameter. Would the velocity remain the same? Assume the tank of water holds 1000 gallons of water. I know i'm not using the metric system here, but its easier for me to visualize this way.

Another way of looking at it, I have a garden hose attached to the water outlet in my backyard. If I put my finger in front of the hose, thereby constricting the exit hole, the water velocity seems to increase. Why? I assume the pressure pushing the water has to remain constant for that to work.

I know i'll be using a gas, but I like thinking of water to understand how its supposed to work.

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