Humans have been using boomerangs for at least 20,000 years.
The ancient Polish used them to hunt animals,
King Tut had a collection of them,
and of course they're an Australian icon.
There are lots of different kinds of boomerangs
and many of them, like the ones used for hunting, aren't meant to return,
they just fly very precisely.
And even the boomerangs that are designed to come back to you are very hard to use.
But if you do it right, you can use aerodynamics to get a boomerang to land neatly in your hands
It works because you're sending the boomerang spinning off at an angle,
but you're also launching it forward, so it ends up with two speeds
a rotating speed and a forward speed.
When combined with the exact shape of the boomerang,
the combination of those two types of speeds makes it turn in a circle as it flies
Boomerangs have two wings that connect at an angle and they're each shaped just like an airplane's wing
in what's known as an airfoil
they have a rounder blunter edge, called a leading edge and a sharp tapered edge, called a trailing edge
and the bottom of the wing is flat while the top is beveled
When air strikes an airfoil, it goes over the leading edge and pushes downwards off the trailing edge
creating a downwards force of air
since every action has an equal and opposite reaction, this downward force of air off the wing
pushes that wing in the opposite direction generating lift
And the faster an airfoil moves through the air, the more lift it gets
Boomerangs only work when they're thrown at an angle
with your arm around twenty degrees away from the top of your head
you flick your wrist so it spins through the air like a propeller
So one wing will be at the top of each spin and the other will be at the bottom
When one wing reaches the top of the spin, it's both moving forward and rotating  forward
and that means it's going faster and generating more lift than the bottom wing
which is rotating in the opposite direction of the forward movement
this unbalancing of forces, called torque, causes the boomerang to tilt and follow a curved path
the circles can be very large or very tight, depending on how fast the boomerang is traveling and at what angle
which is why even if you send it spinning through the air, it takes some skill to get that boomerang to land
softly in your hands, and not over the fence in your neighbor's yard
This question was asked by our Patreon patron Jordan  Francisco
so thank you for the question and thank you to all of our Patreon patrons
who keep these answers coming
If you would like to submit a question to be answered, you can go to Patreon.com/scishow
And if you want to keep getting smarter with us, just go to YouTube.com/scishow and subscribe
