What Is Buoyancy?

Archimedes Principle
Any mass submerged in a fluid at rest has an upward (buoyant) force acting upon it with a magnitude equal to the weight of the fluid displaced.

Archimedes was an inventor and mathematician (c. 287-212 BC) and when he was tasked with weighing King Heiron II's gold crown against other materials to determine if it was made of pure gold, he had to come up with a method of measuring accurately. (1) To do so, he placed the crown in water, the same mass of silver in water, and the same mass of gold in water and observed how much water each test material displaced. He found that silver displaced more water than gold, so when he found that the crown displaced an amount of water that fell between displacements of silver and gold, he could state that the crown was made with both silver and gold. (2)

Types of Buoyancy

• Positive (material lighter than fluid displaced)
• Negative (material denser than fluid displaced)
• Neutral (material weight is equal to fluid displaced) (3)