Throwing Shuriken! / Mr. Denjiro's Happy Energy!
DENJIRO: I'm going to show you ancient weapons called "shuriken," also known as "ninja stars"! Today, we're going to perform an experiment using these stick-shaped shuriken. Let me throw this long shuriken to show you how they move in the air. When we watch it in slow motion, we see that the shuriken spins 90 degrees before hitting the target. This is called the "direct throw method." The center of gravity moves just like a ball does. We can see that the shuriken is spinning with the center of gravity as the axis. If you want to impale a target, you need to be able to control this spin.
Let me explain using this 2D model. Here's the throwing hand and the shuriken. If you simply swing your hand, the shuriken spins too much and doesn't impale the target. But when you throw like you're almost stroking the bottom of the shuriken, you can prevent it from spinning too much.
If you can control how it spins, you can make it impale the target even if the distance changes. I've created a shuriken launcher. When I release the string, the arm of the launcher will be pulled by the rubber bands, launching the shuriken. Let me fire it at the target. It spun 90 degrees, just like when I threw it with my hand.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!"