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DENJIRO: Today, I'd like to show you an interesting toy using a small balloon. This is it. When I smash the balloon against the floor...
BOY: It didn't pop!
DENJIRO: If I did this with a water balloon, it would have popped. But this balloon changes its shape on the floor, and does not pop. It has another interesting characteristic. When I squeeze it or slowly pull it, it changes its shape.
But when I hit it with a wooden stick, it sounds like I'm hitting something hard. It's a mysterious balloon that is soft but hard. Let's see what's inside it. I'll cut the balloon open. This is a starch mixed in water. When I pick up the mixture and squeeze it tightly, it gets hard like this. If I stop applying pressure to it, it becomes soft like a liquid. This phenomenon is called dilatancy.
When you apply pressure to starch particles, the water on the surface moves inside. This makes the surface dry, and therefore, hard. When it gets freed from pressure and left still, the water returns to the surface and it acts like a liquid again.
Here's how to make the balloon. First, we'll mix 200 g of starch with 150 ml of water. But putting this directly into a balloon is difficult, so we'll use a plastic bottle with the bottom cut off like this. There's a small hole on the cap. I'll seal this hole with tape to make a valve. We'll set up the balloon onto the cut-off section of the bottle. Then you put on the cap and suck out the air.
NARRATOR: Pour in the starch mix into the blown-up balloon and tightly tie the balloon, and the dilatant balloon is complete.
ON-SCREEN TEXT: The material will get damaged after long use. Make sure to properly dispose of the balloon after you are done playing with it.
DENJIRO: Try making one and playing with it.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!"