State Archimedes' principle and give its practical applications.

Archimedes' principle states that a body immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the body: F_b = ρ_fluid × V_displaced × g. A body floats when its weight equals the buoyant force. Applications include: designing ships and submarines (hull displacement calculations), hydrometers for measuring liquid density, hot air balloons, determining purity of metals, floatation separation in mineral processing, and analyzing stability of floating structures like offshore platforms.