# The Ancient Greek Scientist Archimedes Principle of Floatation

Archimedes lived from approximately 287 B.C. to 212 B.C. He was a mathematician, scientist, and inventor. He lived in Syracuse, Sicily in Ancient Greece. He explained his floating principle in his work titled “On Floating Bodies”. In his words, “When an object is immersed in a fluid, the upthrust on the object is equal to the weight of the fluid displaced.” It is called Archimedes Principle nowadays. The law of flotation is “A floating object displaces its own weight of the fluid in which it floats.”

Archimedes discovered the floatation concept accidentally after he was summoned by the king to check the purity of a golden crown because the king was not sure of the goldsmith’s competence. One day while he was taking a bath, Archimedes noticed the water in the tub spilled onto the floor. He came up with the idea of putting the golden crown in the tub and measuring the water displaced. He figured he could divide the mass of the crown by the amount of water displaced to find its density.

Dictionary.com defines buoyancy as “The power of supporting a body so that it floats; upward pressure exerted by the fluid in which the body is immersed.” The buoyancy of any object in any liquid follows the same principle. If an object’s density is less than the liquid it is in, it floats when immersed in the liquid. Also, if an object’s density is greater than the liquid it is in, then it sinks when immersed in the liquid. The maximum density of water is at about four degrees Celsius when it is 0.9999720… grams per cubic meter. This makes it about one gram per cubic meter. It is also called a density of approximately one. Its density slowly  decreases as temperatures rise above +4 degrees Celsius (0.9584… at 100 degrees Celsius).

Decreasing temperatures from +4 degrees Celsius also causes a gradual decrease (0.983854… at -30 degrees Celsius).

Aluminum will sink in water because its density is 2.698, which is 2.698-1=1.698 greater than the density of water. Zinc will sink in water because its density is 7.134, or 7.134-1=6.134 greater than the density of water. Tin will sink in water because the density of tin is 7.287, or 7.287-1=6.287 greater than water. Sodium’s density is 0.971, so it will float or sink according to the temperature of water. For example, it will float at +4 degrees Celsius because its density is 0.999-0.971=0.28 less than water. Potassium will float because its density is 0.999- 0.862=0.137 less than that of water.