Quarter Sub - AKA Cartesian Diver

thingiverse

A Fun Toy Demonstrates Archimedes Principle and Boyles Law. Archimedes principle clearly shows that a body fully immersed in a fluid feels a buoyant force equal to the weight of the fluid it displaces. Using Boyle's law, we then change the amount of fluid displaced to make the quarter sub rise and fall. This is achieved by simply squeezing the bottle which reduces the volume of air in the main chamber due to an increase in pressure and this in turn reduces its buoyant force (Boyle’s Law). https://youtu.be/liPob68-oFM