Types of energy

_Elsa_

‘Just as a yo-yo has two kinds of kinetic energy, so it has two kinds of momentum: linear momentum (because it moves in a straight line, up and down on the string) and angular momentum (because it spins around). All spinning objects have angular momentum. And anything that's spinning around likes to keep on spinning so its angular momentum stays the same. If you try to make it spin a different way, it will compensate by changing its motion somehow. If an ice skater is spinning in a circle with her arms out and she suddenly brings them in, she'll spin much faster than she did before. That's because she changes the way her mass is distributed. Her body compensates for this by changing her velocity to keep her angular momentum constant.

Angular momentum is why a gyroscope behaves so strangely. A gyroscope is a heavy wheel mounted on a framework of three axles that allow it to spin around in three dimensions. Once you set a gyroscope spinning, it will strongly resist any attempts to make it spin another way. So if you try to tilt it, it will tilt back the other way. Like an ice skater, it tries to keep its angular momentum constant or, as physicists say, to conserve its angular momentum. A spinning yo-yo behaves just like a gyroscope. That's why it feels strangely stable as it spins on the string. It feels almost as though it has a built-in stubbornness to change its movement. That's one reason why you can do all kinds of neat tricks with it!

The best yo-yos for doing tricks have what's called a centrifugal clutch. It's an extra mechanism of weights (shown here in blue) and springs (black zigzags) built inside the body of the yo-yo that makes it behave differently according to whether it's spinning fast or slow.

When the yo-yo spins fairly slowly, the springs clamp the weights firmly against the axle like brakes so the yo-yo rises and falls on the string (gray line) as normal.

Make the yo-yo spin faster, however, and the weights fly out from the axle because of centrifugal force (or, if you prefer, because the springs cannot provide enough centripetal force to keep them in). Now there's nothing to clamp the axle so it spins freely and the yo-yo "sleeps" at the bottom of the string. When it slows down, the weights go back in again and the yo-yo rises and falls on the string as normal.’ (Source)

Let’s continue - What type of yo-yo is right for me?

Start at the beginning – Let’s learn how to use a yo-yo