5-Minute Video Transcript:

Rocket Science at Home - Hovercraft

Phil: (To camera) Friction is the force that resists motion between two surfaces that in contact each other. It's affected by the type of each surface. and how hard those surfaces are pressing against each other. (Monique places puck on table to start new game, but they don't start game yet.)

Now, here. (references the puck on the table) gravity is the force that's pressing the puck against the table.

Monique: And, of course, anytime you want to keep friction low, you use smooth surfaces,

Phil: Right, because smooth surfaces have fewer microscopic bumps and ridges that have to move past each other.

Monique: So.you're also saying that if the table - or even the puck - were made of a rougher material - like this biscuit (holds up ham & biscuit sandwich).or this ham. (Slaps puck-shaped ham on table) it wouldn't move as well.

Phil: (rolling eyes - laughs) Yes, but actually, another reason the ham doesn't slide is because the water makes it stick to the table. (Picks up ham from table and bites it) Of course this one's pretty dry. it even tastes like a hockey puck. (Tosses ham off screen) (SFX- Glass breaking)

Tim: With air hockey there's something else that reduces friction between the puck and the table.

Phil: (Turns on table to start next game) Right, because turning on the table creates a "cushion of air" between the surface of the table and the puck.

Monique: So, the two surfaces don't actually come in contact with each other. and there's even less friction.

Tim: The less friction you have, the easier it is to move the puck. (He shows off for a while.) You don't need an expert to tell you that that's why it's called "air hockey" and not "ham hockey".

Alexandra: (from worktable) That's also the basic concept of a hovercraft. Lifting a hovercraft on a cushion of air minimizes the force of friction by getting it away from the surface obstacles that it needs to move past.

You can even build your own "mini-hovercraft", with just a few, simple, materials you may already have around your house! For the body of the hovercraft, just use an old CD.

Monique: Hey Alexandra, I see you finally found a good use for your parents' copy of "The Greatest Disco Ballads of the Seventies"!

Alexandra: (Looks around - searching for a CD) Sometimes. you even get CDs sent to you.free in the mail!

Phil: (in pseudo-AOL voice as he hands CD to Monique) "You've got CDs!"

Monique: (joining them at table) But. we still need to create a force that will lift the CD off of the table.

Alexandra: (To Monique) Remember, it doesn't have to leave the table much. just enough to separate the two surfaces. A balloon will do the just the job! (Hands balloons to Phil & Monique.)

Phil: Great! I want purple. (takes balloon)

Monique: Green. (takes balloon)

Alexandra: You can use these push-pull bottle caps, as a nozzle (shows bottle top) to attach the balloon to the CD.

Phil: You can use other things to attach the balloon, but these work great, because they let you to shut off the airflow until you're ready for it.

Alexandra: To build the hovercraft, simply attach the bottle top to the center of the CD using a silicon caulk or silicon household glue.

After it dries, blow up the balloon, twist it shut to hold in the air, and stretch it over the top of the nozzle.

Set the CDs on a smooth surface to test, and when you're ready to go. lift up the nozzle to release the air.

Phil: (as CDs are moving) Whoa!

Alexandra: You now have a "mini-hovercraft" of your very own! (They all play with the mini-hovercrafts for a few moments.)

Monique: Check out how some students in Hailey, Idaho took the hovercraft concept to the next level and built one that they could actually ride!

Brad Thode: What we're going to do is overcome friction. So.what we have done here is we've made a homemade hovercraft. This is actually made with a vacuum cleaner motor. So we're using the exhaust - the part that comes out of the vacuum and we're using that to create pressure.

So, if we can get him off the ground - just by using a little bit of air pressure, we can reduce that friction.(starts hovercraft) and now. he's floating. he's hovering. (turns off hovercraft)

So what we've done is we've taken every square inch. underneath here and put a. just like a tenth of a pound - maybe not even that - of .of air pressure and because it's spread out over hundreds of square inches, we can lift heavy loads.

Phil: If you like the idea of building a hovercraft you can ride, why not get the help of an adult and give it a try? Be sure to follow all instructions and the safety procedures on the website and for your tools.

Now when you're done, the base of the hovercraft should look about like this. The plastic and the plywood form a big bag and the air comes in through a large hole and out through all these small holes. When I connect the leaf blower, or the shop vac, this is what happens.

See, the bag fills up with air and all the little holes release that air onto the floor and lift you off.

When you shop for materials, don't forget to get all of the safety gear you'll need as well. Remember, you can find all this at your local hardware store.

Alexandra: And you can find more details on how to build your very own hovercraft at NASA's website. Once there, check out how NASA uses the "hovercraft" concept to train astronauts for spaceflight.