The Science of Bottle Flipping

Hey guys, so unless you’ve been living under a rock, chances are you’ve, heard of the water bottle flip challenge. You know, where you take the water bottle, flip it up, and — tada, it lands perfectly upright. Or at least that’s what’s supposed to happen, and this, no joke, was my first try. But, with that being said, there’s a lot of interesting physics that goes into this simple trick. When you flip a water bottle, you give it angular momentum. Which is really just a fancy word, for how much energy a rotating object has. But not only do you give it angular momentum. The water in the bottle produces its own angular momentum as well. When you rotate a bottle of water, A little bit of water will get to the other side, before the rest. And this little bit of water has mass. Which pulls down the water slightly. Adding a little bit more water, and a little bit more mass. And this shifts the center of gravity, just slightly. But that water has more mass, and that attracts more water, and more water. And this shifts the center of gravity further, and further. Until the majority of the water, is on the other side. And the center of gravity has completely shifted. At this point, the water bottle continues rotating. And completes the cycle over, and over again. Now, you wouldn’t really think that the added angular momentum, from the uneven weight of the water, would really make that much of a difference. But, it really does. As we can see: when we flip this one, it has a lot of ‘flip’. Whereas, when we flip this one, that’s almost entirely full, and acts more like a solid: It doesn’t flip nearly as much. This bottle is so full of water, that it doesn’t have enough extra space, for the water to swish around. On the flip [haha] side, a bottle with too little water, won’t be able to flip properly, aswell. As the water is not able to swish around, when you swing it. So that means, when you flip it, it’ll just end up rotating around the heavy base. In addition to not being able to flip properly; a bottle without enough water, doesn’t have enough mass to remain stable, when you drop it. A bottle with too much water, is also unstable. The center of gravity on this bottle, is really high. So when you drop it, it’s too unstable to stay up. As we can see, in a bottle that’s about one-third of the way full, When you drop it, it has just the right amount of mass. To keep it stable. Now, putting in enough water, is the easy part. The hard part, is giving it JUST enough angular momentum, and JUST enough arc. So that just as this water bottle is making one full rotation, the mass at the bottom over weighs that angular momentum, and pulls it down. Thank you so much for watching! If you enjoyed watching this video, as much as enjoyed creating this video; Then please leave a like! Or Subscribe. Thanks!