How Does A Boomerang Work?

[Taps] [Zene]

How does a boomerang work? Well, it relies on three fundamental principles: lift, relative velocity, and gyroscopic precession.

Now, a traditional Australian boomerang is basically just two wings stuck together, and both generate lift that keeps the boomerang in the air. But the thing is, as the boomerang is rotating, the top actually rotates with the direction the boomerang is moving, while the bottom is rotating in the opposite direction.

So, air flows faster over the top of the boomerang, creating more lift than over the bottom. Those unequal forces generate a torque, and you might expect that torque to flip the boomerang over, but it doesn't. That's because the boomerang is thrown with a very fast spin, so that spin means that the boomerang has angular momentum—a significant amount of it.

If you want to figure out which direction that is, you put the fingers of your right hand in the direction of rotation, and your thumb points in the direction of the angular momentum. So, as it's spinning, that torque actually changes the angular momentum. It changes the angular momentum in the direction of the torque, and the torque in this case is back towards me.

So, the angular momentum is changed to point around at me, allowing this boomerang to execute its curved path and come back to where it started. That phenomenon is known as gyroscopic precession.

Now, if you want to see an awesome boomerang shot, you got to check out how ridiculous they tried to split an egg with a boomerang. They've done lots of other cool tricks, like catching a frisbee from a speedboat. So you got to check it out and subscribe to their channel, and then come back to me, and I will explain the physics of all of it to [Zene].

You [Zene]

Other fun facts about boomerangs: although we usually associate them with Australia, they've also been found in places like ancient Egypt and Europe. Some of them apparently are non-returning boomerangs, and that makes—ask makes it a boomerang if it doesn't come back to you.

Some people call those throwing sticks, which I think sounds like a more appropriate name for something that doesn't come back to you. You know, we even tried boomerangs in space! So a boomerang will still fly; it will still go around, even in zero gravity.