Balloons & Buoyancy 

Balloons & Buoyancy is a physics and chemistry simulation tool. It of course deals with buoyancy. In this particular simulation, balloons are used to recreate conditions that influence an object buoyancy. In lay terms, buoyancy is an object's ability to float. An object can float not only on water, but on other liquids and even gases as well, as it is in the case of helium balloons.