Elatusvoima

Elatusvoima, or buoyant force, is the upward force exerted by a fluid on a body immersed in it. It results from the pressure distribution within the fluid: pressure increases with depth, producing a greater force on the bottom of the object than on the top. According to Archimedes’ principle, the buoyant force equals the weight of the fluid displaced by the object: F_b = ρ_f g V_submerged, where ρ_f is the fluid density, g is the acceleration due to gravity, and V_submerged is the submerged volume. The force acts upward and through the center of buoyancy, the centroid of the displaced fluid.

The net vertical force on the object is F_net = F_b − m g, with m the object's mass. If the object has density ρ_s and V_submerged is the immersed volume, then F_net = g V_submerged (ρ_f − ρ_s). When ρ_f > ρ_s, the buoyant force overcomes weight and the object rises; when ρ_f < ρ_s, it sinks; and if ρ_f = ρ_s, the object is neutrally buoyant.

Applications of elatusvoima are widespread. Ships and submarines are designed to balance buoyancy with weight to achieve flotation and submersion control. Hot air balloons rise because the hot air inside is less dense than the surrounding air, creating a buoyant force. Buoyancy is also used in density measurements and devices like hydrometers, as well as in scuba diving and various fluid-dynamics contexts.

In summary, elatusvoima is a fundamental hydrostatic force governing flotation and vertical motion in fluids, determined by displaced fluid mass and the surrounding fluid’s density.