State Archimedes' principle. - Leaving Cert Physics - Question (a) - 2007

Archimedes' principle states that the upward buoyant force or upthrust experienced by a body immersed in a fluid is equal to the weight of the fluid displaced by that body. This principle can be mathematically expressed as:

$F_b = W_d$ where:

• $F_b$ is the buoyant force (upthrust) acting on the body,
• $W_d$ is the weight of the fluid displaced.

In simpler terms, when an object is submerged in a fluid, it experiences a loss in weight which is equal to the weight of the fluid it displaces.