>> Stored energy is called potential energy, because it has the potential to do work.

One way to build potential energy is to raise an object against gravity, like biking up a hill.

Once at the top of the hill, stored energy can now be used to do work.

If a bike coasts down the hill, gravity then converts potential energy into kinetic energy, or energy of motion, by pulling the bike down the hill.

And there are many ways to convert potential energy into kinetic energy.

>> Yeah, like water.

Kind of like a water wheel.

>> Water?

>> Yeah, like water.

You know, I want to smack you.

>> How do you mean?

>> Like, as you pedal, for example... >> Try it.

>> Well, okay.

As you pedal... say this is the back wheel of the bike.

Let's just say you pedal, it drives water up.

>> Pedaling a pump.

>> Yeah, that'll force the water into this big container, okay?

There's your potential energy, because gravity will drive it down.

>> Like, if you have cups in here where you put water in, like here, and this is a rotisserie, so the water falls down, it makes the big wheel spin, which spins the rotisserie.

So let's get started with a design.

Want to draw it out?

>> Yeah, let's draw it out.