The Science of Bottle Flipping

Remember this fad? While the initial fever seems to have worn off, every so often it loops back around in my house and that familiar “Ka-chunck” echoes from the rafters, accompanied by cheers and groans of my boys.

While adults might be immune to the charms of bottle flipping, kids understand the pure sense of accomplishment that comes from perfecting the incredibly difficult skill of tossing a water bottle so it lands upright.

Why is it so hard? Science.

You know how to achieve the perfect flip the bottle has to be a certain shape? You know how you can’t have too much or too little water inside the bottle? Bottle flipping comes down to physics—having the right amount of water in a bottle that’s given just enough force when tossed into the air.

When you release the bottle and put it into a spin, you’re applying angular momentum to the water bottle. Angular momentum is the force that keeps the bottle spinning, just like regular momentum is the force that keeps a ball rolling until something, such as friction or a person, stops it. 

But the water in the bottle is much heavier than the bottle itself—it has more mass. The water slows the angular momentum of the bottom of the bottle down. And when the water is pooled in the bottom of the bottle, gravity supplies another force, pulling the water, and therefore the bottle, to the ground and stopping the angular momentum completely.

So kids, you might think you’re just flipping bottles and annoying the adults around you, but you’re really exploring the physics of angular momentum, fluid dynamics, and gravity. 

Which is flippin’ awesome.