Science Articles

Archimedes’ Principle

Archimedes is considered by many as the greatest scientist of the ancient world. Born in Syracuse, Greece, in 287 BC, Archimedes was equally adept at Mathematics, Physics and Astronomy, besides being a prolific inventor and engineer. Among his many inventions is the Archimedes screw, the Archimedes Claw, the heat ray, the block-and-tackle pulley, the odometer, an improved version of the catapult and the basic principles for the for the lever. Many of his inventions, theories and concepts are still in use today.

Archimedes is considered by many as the greatest scientist of the ancient world. Born in Syracuse, Greece, in 287 BC, Archimedes was equally adept at Mathematics, Physics and Astronomy, besides being a prolific inventor and engineer. Among his many inventions is the Archimedes screw, the Archimedes Claw, the heat ray, the block-and-tackle pulley, the odometer, an improved version of the catapult and the basic principles for the for the lever. Many of his inventions, theories and concepts are still in use today.

However, Archimedes is best remembered for his discovery of the principle of buoyancy. The moment when he discovered it has gone down in history as the “Eureka” moment. The phrase too has entered popular lexicon to depict “a moment of sudden, triumphant discovery, inspiration, or insight” (as defined by Merriam Webster Dictionary).

The Story Behind The Discovery of The Archimedes Principle-

Hiero, the King of Syracuse, had given an exact quantity of pure gold to a goldsmith to craft a golden crown for him. However, he suspected that the goldsmith had cheated him by keeping some of the gold for himself, and mixing some silver with the gold to make the crown. The King asked Archimedes to investigate the truth behind the purity of the crown.

A few days later, while taking his bath, Archimedes noticed that the water level in the bathtub rose to the brim of the tub and overflowed as he immersed himself into the bathtub. All of a sudden, he was hit by the realization that the amount of water that was displaced depended on how much he immersed his body into the bathtub.

The realization excited him so much that he jumped out of the tub and ran naked through the streets of Syracuse shouting, ‘Eureka, Eureka!’, which is Greek for ‘I have found it!.  Well, what Archimedes had found was a way to determine the amount of pure gold used in the King’s crown.

Archimedes knew that gold was heavier than other metals. Thus, if he immersed the crown in a tub of water, and if he also immersed an equal amount of gold in another tub of water of same volume, he could determine the gold in the crown by the amount of water displaced in both tubs. If the crown displaced less water than the pure gold lump, it meant that the crown was made with a mix of gold and some other metal.

At the end of the experiment, Archimedes found that the goldsmith had indeed cheated the King by mixing silver with the gold in the crown. In this way, Archimedes was able to solve the King’s problem.

The Archimedes Principle-

The Archimedes Principle states that-

“When a body is immersed, partially or completely, in a liquid, it experiences an upthrust and the magnitude of this upward force or upthrust is equal to the weight of the liquid displaced by the body.”

This principle applies not only to liquids, but also to gases.

Uses Of Archimedes’ Principle-

The Archimedes Principle is useful in explaining the behaviour of an object when placed in a fluid. It explains why ships float, hot air balloons rise up into the sky and how submarines dive. It can be used to determine the densities of various substances and liquids. The hygrometer works on the Archimedes Principle. Besides this, the principle has a lot of applications in fields as diverse as dental, medical, geology, entomology and engineering.