# THE SCIENCE OF BOTTLE FLIPPING

The Amazing Flip It Bottle™ is a game of science as much as it is a game of skill and chance. At the core of The Amazing Flip It Bottle™ there is a whole lot of physics going on, beginning with the idea of the conservation of angular momentum. The angular momentum of an object depends on its moment of inertia (how much the mass of an object is spread out from a specific central point) and its angular velocity (how fast the object is spinning). When no external twisting or turning force, called ‘torque’ influences an object, its angular momentum must be conserved. The best example of this is an ice skater who is spinning. If the ice skater begins spinning with their arms open, she has high inertia (because her mass {arms} are spread out from the rest of her body {which acts like the central point}. If the ice skater pulls their arms in tightly, their inertia decreases. In order for angular momentum to stay the same, their angular velocity must increase in order to spin faster.

Now, you may be wondering what this has to do with competitive bottle-flipping?

Let’s begin by imagining if you toss a solid item such as a coin through the air. Eventually gravity will cause the coin to land on the ground. Now, since the coin is a solid, its mass does not change as it moves through the air, and its inertia and angular velocity will remain the same. Because it is a solid object, inertia and angular velocity do not change, making it difficult for someone to guess what side the coin will land on. But a water bottle is very different than a solid object like a coin. And the design of The Amazing Flip It Bottle™ and it’s uniquely designed caps and bottles demonstrates the effects of physics to ramp up competitive bottle flipping play.

You see, a bottle is different since it contains a liquid, which will move around the bottle and change its distribution of mass as the bottle spins and turns as it moves through the air. As the bottle continues to spin in the air, the bottle’s inertia and angular velocity are also changed (because the total angular momentum will stay the same).

Now, there are many factors that will impact a person’s ability to land a bottle on its base or the more difficult challenge of landing it on its cap. This includes how many times you flip the bottle in the air, how high you flip the bottle, and the amount of liquid in the bottle... amongst other factors. When The Amazing Flip It Bottle™ team was designing our bottle and cap designs our engineering team focused on the physics at play for competitive bottle flipping and incorporated our discoveries into our unique designs.

At the center of of all bottle flipping is the idea of angular momentum.

As a reminder, angular momentum must always be conserved if no outside torque acts on an object, and it depends on angular velocity and inertia. So when a bottle is flipping in the air, there is no torque put on it. And remember that the inertia of an solid object like a bottle will not change its spin, which causes the bottle’s angular velocity to stay the same making it hard to control the bottles landing position. The same principles are at work when a bottle is full of liquid because there is no room for the liquid to move around thus the distribution of mass inside the bottle will remain the same, causing its angular velocity to also stay the same.

However, when a bottle is partially filled with water when it is flipped, the water moves around the cylinder, thus increasing the inertia and decreasing the angular velocity – which conserves angular momentum – causing the bottle’s spin to slow as it flips through the air. This will make it possible for the bottle to land either on its base (much easier) or on its cap (more difficult). The Amazing Flip It Bottle™ team discovered that there are design mechanisms of the bottle and cap along with the amount of liquid placed in a bottle that increase the likelihood of landing a bottle on either its base or cap.

The Amazing Flip It Bottle™ and Amazing Flip It Bottle™ Caps are aerodynamically designed to increase the likelihood of landing on its base or cap and can increase a bottle flippers advantage in competition. We focused on the science and the engineering to create the most dynamic bottle flip bottles and caps so that you can dazzle your friends with amazing tricks and increase your skill set!