In 1985 an astronaut noticed this physical behavior of a handle, that turned out to be the proof of a theorem: the tennis racket theorem (also dubbed the Dzhanibekov effect)

For those who have no idea about theorem effect.. Imagine you have a tennis racket, and you want to toss it in the air and catch it. You can spin the racket around three different axes: the handle, the face, or the edge. If you spin the racket around the handle, it will keep spinning smoothly and not flip over. This is because the handle is the longest and heaviest part of the racket, and it has the most resistance to change its rotation. This is called the major axis of the racket. If you spin the racket around the face, it will also keep spinning smoothly and not flip over. This is because the face is the widest and flattest part of the racket, and it has the least resistance to change its rotation. This is called the minor axis of the racket. But if you spin the racket around the edge, something weird will happen. The racket will start to wobble and flip over, even if you try to spin it very carefully. This is because the edge is the shortest and thinnest part of the racket, and it has an intermediate resistance to change its rotation. This is called the intermediate axis of the racket. The reason why the racket flips over when you spin it around the intermediate axis is that the rotation is unstable. This means that any small disturbance, such as air resistance, gravity, or your hand movement, will make the racket change its direction and speed of rotation. The racket will try to switch to a more stable rotation, either around the major axis or the minor axis, by flipping over. This is what the tennis racket theorem or the Dzhanibekov effect is about. It says that any object that has three different axes of rotation, like a tennis racket, a book, or a wing nut, will flip over when it is spun around the intermediate axis. This effect can be seen in space, where there is no gravity or air resistance, but also on Earth, where these forces are present. The astronaut who noticed this effect in 1985 was Vladimir Dzhanibekov, a Soviet cosmonaut who was on board the Salyut 7 space station.

The Dzhanibekov Effect The intermediate axis theorem, also known as the tennis racket theorem, is a classical mechanics description of the motion of a rigid body with three distinct principal moments of inertia. This means it requires a different amount of torque. 📹 @draainhp

Physics are Fun

Imagine if we really dug into the Dzhanibekov effect further. What if, the bigger the object, the more spins it needs before flipping out? Now picture Earth playing this cosmic game of spin-the-bottle. Every 91,250 spins (about 250 years), it decides, "Eh, let's switch the poles!" – a planetary mood swing that resets civilization like a giant etch-a-sketch. Maybe that's what happened to Atlantis – they just got Dzhanibekov'd! So, next time the planet starts acting up, remember, it might just be gearing up for its once-in-a-millennium flip! 🌍💫

The Dzhanibekov effect is a result of the complex interactions between the object's moments of inertia and the conservation of angular momentum. It has implications for understanding the dynamics of rotating bodies in space and has been studied in both theoretical and experimental contexts.

I first discovered this for myself while tossing a hammer in the air. Regardless of the toss the hammer always did a flip spin at the moment of weightlessness. Or the moment the upwards force on the hammer was equal to the gravitational force acting on it. I assumed at the time that it was exactly what would happen in zero gravity. I was correct

The Dzhanibekov effect, also known as the Tennis Racket Theorem, is a phenomenon in rotational mechanics named after Soviet cosmonaut Vladimir Dzhanibekov, who first observed it in space. The effect demonstrates an unusual behavior of rotating rigid bodies.

wow, watching it move is cool but I don't know how to apply it in practice, please help me answer, it looks interesting or unique

Earth does this as well. You just have to 'Hold On'. 😉

Impressive..