How does a yoyo work?

QUESTION: How does a yoyo “sleep” at the bottom so that you can do tricks? What makes a yoyo actually work?

ANSWER: A big difference between a real yoyo and the cheap ones you sometimes find at a dollar store is the string.

Cheap yoyo-like toys generally have the string tied in a knot or glued to the axle. So when you throw them down, they will just immediately wind back up. They can’t sleep at the bottom and they can’t do any real tricks.

But a real yoyo uses a special yoyo string that loops around the axle. That means when you throw the yoyo down spinning, it can go to the bottom and keep spinning inside the loop. At that point, you need to give it a tug to make it “wake up” and come back to your hand.

It uses the energy of the spin from your downward throw to wind back up the string. So that’s why if you let it sleep too long, it won’t come back. It used up all the energy spinning at the bottom and didn’t have enough left to climb all the way back up the string to your hand.

A good yoyo player knows how to throw the yoyo with high efficiency and put a lot of energy and spin into the yoyo, so that it sleeps a long time and can do longer tricks. If you’re a beginner, it takes a while to develop the skill to make it sleep at all, or even go straight down and come back to your hand!

When the string is wound up and you are holding the yoyo in your hand, you have potential energy. And when you throw the yoyo down to unwind the string, it turns the potential energy into kinetic energy.

The yoyo is round with an axle that spins inside the looped string. That spinning gives it gyroscopic stability and keeps it from flopping over. The pull on the string creates a force against the bottom of the loop and causes the yoyo to grab on and wind back up into your hand.