Archimedes

Although he lived over 2000 years ago, Archimedes of Syracuse (287-212 B.C.) is still regarded as one of the greatest physical scientists of antiquity.   High school physics students are probably familiar with at least two stories involving Archimedes:

• When describing the mechanical advantage gained by the use of a lever, Archimedes is claimed to have boasted:   "Give me somewhere to stand, and I will move the earth."

• Having discovered, supposedly while in the midst of his bath, a method for determining whether the King's crown had been made of pure gold or a cheaper alloy, Archimedes is said to have run naked through the streets shouting:   "Eureka!"

It is by the latter of these two events that Archimedes is credited with discovering that a body immersed in a fluid is buoyed upward by a force equal in magnitude to the weight of the fluid displaced by the body.   This relationship has thus come to be known as Archimedes' Principle.   The upward force is a consequence of the fact that there is increasing pressure with increasing depth in a fluid in a gravitational field.