Now, what we've got here, pop bottle. This is basically our water rocket here. Now, well,

how way a water rocket works is you put water in, and then you pressurize it. You pump air

into it, and that's what this complicated apparatus here is for. I've built many different

launchers over the years, but I've never been able to build one quite as nice as I was able

to buy, at sciencekit.com. A wonderful little launcher here. The ah, stand is extra. The

original launcher just has a pair of stakes you can hammer into the ground, and that works

just as well. But if you're working on concrete or asphalt, the stand is essential. I've taken

a second water bottle here and I cut the top in order to make it a little bit more aerodynamic.

You can slide the top right on the top. Now, if you're really fancy, you can go ahead and

add some fins on there. My friend, Tim, built this wonderful one. It's got a recovery system,

fins and everything. These fins are off an old bottle rocket that's seen better days,

so we recycled them onto this rocket, and this works wonderfully, but we're going to

keep it simple today. Now, in order to launch this, you gotta get a little bit of water

in there.

Put the plug with the valve in,

invert it, now there are two keys here, two clamps, that hold it in. And then, there is

a key that fits in to tightly hold this together, and we've got a pump here.

As we pump air in, it pressurizes. Now that air wants to get out, but there's a fair amount

of water in the way, so when we pull this pin out outdoors, it's going to push the water

out of the bottom of the rocket. Now, Newton says every action has an equal opposite reaction,

so the force pushed out of the bottom of the rocket is going to push the rest of the rocket

up and that's how every rocket works. Our model rocket uses chemical energy to do that.

This, we're just pressurizing. We're putting air in here which will push the water out

the bottom and push the rocket up. Let's head outside and launch this. We're ready to launch

the water rocket. Five, four, three, two, one! And that's how you launch a water rocket.