buoyancyfloating

Buoyancy floating is the behavior of objects in a fluid under the influence of buoyant forces that oppose gravity. It describes why some objects rest on the surface, others float with part of their volume submerged, and still others remain underwater if heavier than the surrounding fluid. The phenomenon is governed by Archimedes' principle: the upward buoyant force equals the weight of the fluid displaced by the submerged portion of the object. Mathematically, F_b = ρ_fluid g V_submerged, and the weight of the object is W = ρ_object g V_total. At equilibrium, a floating object satisfies ρ_fluid g V_submerged = ρ_object g V_total, so the submerged volume V_submerged = (ρ_object/ρ_fluid) V_total. If ρ_object < ρ_fluid, the object floats with a portion above the surface; if ρ_object > ρ_fluid, it sinks; if equal, neutral buoyancy occurs.

Stability of floating bodies depends on the relative positions of the center of gravity and the center of buoyancy. When the object tilts, the center of buoyancy shifts, creating a restoring or overturning moment. A positive metacentric height indicates stable floating.

Practical examples include ships and boats, which adjust buoyancy with ballast; submarines, which modify buoyancy to dive or surface; and lighter-than-water objects such as balloons and life jackets. On very small scales, surface tension can contribute to buoyancy for tiny objects at a liquid interface.