Archimedes Principle states that the buoyant force on an object equals which quantity?

• A. The weight of the object
• B. The pressure at the object's surface
• C. The weight of displaced fluid
• D. The density of the object

Answer: (C)

Archimedes principle says the buoyant force pushing up on an object in a fluid equals the weight of the fluid that the object displaces. In other words, the upward force is set by how much fluid is moved and how heavy that fluid is. Mathematically, that force is ρ_fluid × g × V_displaced, where ρ_fluid is the fluid density, g is gravity, and V_displaced is the volume of fluid pushed aside.

This is why ships float: they push aside a certain volume of water until the weight of that displaced water matches the ship’s weight, and the net force becomes zero with the ship at rest. It also explains why a submerged object feels an upward push that depends on how much fluid it pushes away, not on the object’s own weight or its density alone. The weight of the displaced fluid is the key quantity, and that’s what sets the buoyant force.