Archimedes's principle
From Glossary of Meteorology
The statement that a net upward or buoyant force, equal in magnitude to the weight of the displaced fluid, acts upon a body either partly or wholly submerged in a fluid at rest under the influence of gravity.
This force is known as the Archimedean buoyant force (or buoyancy), is independent of the shape of the submerged body, and does not depend upon any special properties of the fluid.
