Buoyancy "downward" direction. The center of buoyancy of an object is the centroid of the displaced volume of fluid. Archimedes' principle is named after Archimedes of Syracuse, who first discovered this law in 212 B.C. For objects, floating and sunken, and in gases as well as liquids (i.e. a fluid), Archimedes' principle may be stated thus in terms of forces: — with the clarifications that for a sunken object the volume of displaced fluid is the volume of the object, and for a floating object on a liquid, the weight of the displaced liquid is the weight of the object. More
Buoyancy aid should detail: For a buoyancy aid to be sold in the European Union, it must be C.E. tested and approved. Buoyancy aids with providing only 50 N of force should only be used by swimmers in sheltered waters when help is close at hand. They are not guaranteed to turn a person from a face-down position in the water. The foam used in buoyancy aids does degrade with age. Manufacturers add additional foam to ensure that their buoyancy aids will still provide enough force even after years of use. A rough life expectancy is three years of use, although buoyancy