Which ancient mathematician is credited with the buoyancy principle and the exclamation 'Eureka'?

• A. Archimedes
• B. Euclid
• C. Pythagoras
• D. Heron

Answer: (A)

Buoyancy arises because a fluid pushes upward on anything submerged in it, and the upward force equals the weight of the fluid that is displaced. Archimedes formalized this relationship, now known as Archimedes’ principle, which explains why objects float or sink and how you can determine an object’s volume (and thus density) by measuring how much water it displaces. The famous cry “Eureka” comes from a story about Archimedes realizing how to test the purity of a crown by observing the water displaced when the crown was submerged. This idea connects the volume of an object to the weight of the fluid it displaces, underpinning practical methods in measuring density and in designing floating objects. For contrast, Euclid is celebrated for geometry, Pythagoras for the theorem and early number theory, and Heron for various inventions and formulas, not buoyancy.