At some point in your life you’ve certainly played with a yo-yo, right? It is one of the oldest toys of mankind. The yo-yo may have sprung up in China or other regions of the East, but its earliest records are from 500 B.C. in Greece.

But as a child, you probably have not stopped to think about the several physical laws that act on this toy. So, take a look:

The physical laws and the yo-yo

Basically, the yo-yo’s operation can be explained by the principle of conservation of energy. However, to be clearer, it’s needed to explain what happens at each step of this game:

• Still in hand: while holding the yo-yo, it has a certain amount of potential energy;
• On the descent: at the time the toy is released, the force of gravity pulls it down, making the movements of rotation and translation. As it descends, the potential energy is converted into kinetic energy;
• At the end point: when the yo-yo reaches the endpoint of the cord, it suffers a force upward because the wire has run out and then spins at the same point for a few seconds. At this moment, it has only rotational kinetic energy. Because of the inertia, it tends to be spinning at this point until some external force acts on it;
• On the uphill: when it’s pulled down, the yo-yo’s shaft climbs back up the cord. As it rises, it gets kinetic translational energy again, which decreases until it returns to potential energy and reaches on hand.

Did you like to understand better about the physical laws that act on the yo-yo? Discover other physical curiosities on our blog.