Eli5: how does this apple float in place, and why does it also explode?


So there’s this video I just watch. Can someone explain to me how this apple floats in place, and why it doesn’t drop or fly somewhere else? And why is it when the RPM of the apple gets higher it explodes?

[Apple grenade](https://youtu.be/HcNsQyDaVng)

In: Physics

I watched the video without sound, so I don’t know if they said it but:

The thing the guy is holding is a valve for compressed air. So a jet of air shoots out the end and hits the apple. The apple weighs just enough to have the air push hard enough to balance the weight and kleep it afloat.

The *explosion* is less an explosion and more a being ripped apart.

I bet you did it as a child too. Eithe on an office chair or one of those spinning carrousel.

Everybody holds on to the beans and one kid runs around (later standing still) and spinning the carrousel faster and faster.

At one point you just can’t hold on anymore and you fly out and land in the dirt laughing.

This is very much what is happening here. The centrifugal force (the force that you feel is pulling you outwards on the carrousel, or pushing you into the side in a car going around a curner) is just so big that the apples doen’t hold together anymore.


The apple stays afloat because of [Bernoulli’s principle](https://en.wikipedia.org/wiki/Bernoulli's_principle). Air flows faster across one side, which creates a low-pressure zone attracting it. It’s the same physics that work on airplane wings and why your shower curtains like to cuddle.

Since the faster air also pushes a bit on that side of the apple it starts to rotate. At a certain rotation speed the centrifugal force (the same that pushes you off a merry-go-round on the playground) gets stronger than the forces holding it together and you have spontaneous rapid disassembly.