How Do Boomerangs Come Back To The Thrower?

To be honest, I’ve always wondered that: how on earth, do boomerangs always come back to you? I mean, how is ti possible to throw an object into the air and then just watch it fly and return to your hands?

I’ve always found it fascinating. I don’t know why i didn’t write about this earlier but hey, better late than never, right?

So, after reading a lot of boomerang-related articles, such as this geeky essay by the Maths Department of the University of California, Irvine, i finally “got” it. (the article continues after the ad)

Before we get into it, just a short history lesson: boomerangs didn’t always come back. This specific tool was used by humans as a weapon for more than 30,000 years. They way it worked was simple: one would just throw it at an animal and hopefully, it would hit and kill it. No one knows for sure since when we started designing boomerangs that would return back. In fact, their invention might as well be an accident.

Anyway, back to our basic question: why do boomerangs come back?

Well, as it turns out, it all has to do with its shape and a phenomenon called gyroscopic precession. The wings of a boomerang are just like a plane’s wings; in the shape of an airfoil (flat at one end and curved at the other) in order to provide the necessary lift:

Photo: Acheson, Elementary Fluid Dynamics

Here’s what happens when a boomerang is thrown vertically (as it should) though: the top wing will generate more lift than the wing at the bottom, because the top wing moves in the direction of the throw while the bottom wing moves in the opposite direction. This difference in the lift will eventually create a torque and it’s that torque that will tilt the boomerang and make it return back to the thrower:

Photo: Georgia State University

And now you know!

What you don’t know is how to properly throw a boomerang, so here you go:

If you like what you read, then you will definitely love this one: How Do Silencers Work And Why They Are Nowhere Near ‘Silent’ 

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Photo:  Wikimedia
Photoshop: I’m A Useless Info Junkie
Sources: What Makes Boomerangs Come Back?  | Boomerang as Vector Rotation Example

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