Archimedes' Principle
The principle stating that any object fully or partially submerged in a fluid experiences an upward buoyant force equal to the weight of displaced fluid.
Governing formula
Fb = m_fluid g = ρ_fluid V_displaced g
SI unit
N
In depth
Objects float if their average density is less than fluid density (ρ_obj < ρ_fluid), sink if greater, and remain neutrally buoyant if equal.
Examples in the real world
Submarines adjusting water ballast tanks to control buoyant density and depth.