DENJIRO: Have you ever played with a pogo stick? There’s a large spring in the middle that allows you to jump up high. You know, it’s actually hard to explain why a spring stretches and shrinks.
Let me explain the principle behind how a spring works. I have here a metal wire and a spring. Even if I pull on the metal wire, it doesn’t stretch. But the spring does. So what exactly is the difference here? You can’t stretch the wire, but you can twist it like this. This twist is the key to a spring.
I’m going to use this cord so we can better see how a spring twists. I’m going to wrap it around a rod. Now I’m going to take the cord off. It’s a spring. Watch what happens if I stretch it. You can see that it’s twisted. It’s twisted the same number of times I wrapped it around the rod. When I shrink it, the twist returns to its original state. This is how a spring stretches and shrinks. A spring will twist and untwist when it is stretched and shrunk. The twist of a metal wire is the principle behind how a spring works.
It's actually possible to make a spring with glass too. Let me show you. Here it is. As you can see, it can stretch. Even if this spring stretches and shrinks, the difference in its twist is minimal. That’s why you can make a spring with a thin, delicate piece of glass.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!”