Frostbite Theater

Announcer: Frostbite Theater presents... Cold Cuts! No baloney!

Joanna and Steve: Just science!

Joanna: Hi! I'm Joanna!

Steve: And I'm Steve!

Joanna: Here's a question for you...

Steve builds a toy car. He attaches a magnet to it and, to make it go, he holds a second magnet close to it.

Tired of holding the magnet, Steve changes the design of the car so that the second magnet is suspended in front of the magnet attached to the car.

When Steve lets go of the car, which way will the car move?

Steve: Will it move to the right?

Joanna: Will it move to the left?

Steve: Do you not know, because we haven't told you if the magnets have opposite poles facing each other or like poles facing each other?

Joanna: Or, will it not move at all?

Steve: Pause the video now if you'd like to think it over before we show you what happens.

Joanna: An object at rest will remain at rest unless acted upon by an outside force. Since both magnets are attached to the car, they don't provide an outside force.

Steve: There are a few design changes we can make that should make this clear.

First, we can get rid of the string and just attach the magnet to the angled beams.

And, then, there's really no need for the beams to be angled. They can just be straightened out.

And then both magnets can be scooted over so they're both inside the car.

So, here is an equivalent design. One magnet in front. One magnet in back. If I let go of the car, which way will it go?

Joanna: It doesn't.

Thanks for watching. I hope you'll join us again soon for another question!