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Buoyancy aids for sea and long-distance touring often feature several large pockets for storing essential equipment, and many also accommodate hydration packs. They have to be comfortable to wear whilst paddling for long distances, and so typically have very low cut sides to allow the arms free movement.
(This formula is used for example in describing the measuring principle of a dasymeter and of hydrostatic weighing.) Example: If you drop wood into water, buoyancy will keep it afloat. Example: A helium balloon in a moving car. When increasing speed or driving in a curve, the air moves in the opposite direction to the car's acceleration.
Buoyancy also applies to fluid mixtures, and is the most common driving force of convection currents. In these cases, the mathematical modelling is altered to apply to continua, but the principles remain the same. Examples of buoyancy driven flows include the spontaneous separation of air and water or oil and water.
Personal flotation devices being worn on a navy transport . A personal flotation device (PFD; also referred to as a life jacket, life preserver, life belt, Mae West, life vest, life saver, cork jacket, buoyancy aid or flotation suit) is a flotation device in the form of a vest or suit that is worn by a user to prevent the wearer from drowning in a body of water.
Neutral buoyancy occurs when an object's average density is equal to the density of the fluid in which it is immersed, resulting in the buoyant force balancing the force of gravity that would otherwise cause the object to sink (if the body's density is greater than the density of the fluid in which it is immersed) or rise (if it is less).
The lifting power in air of hydrogen and helium can be calculated using the theory of buoyancy. The buoyancy depends upon the difference of the densities (ρ air) − (ρ gas) rather than upon their ratios. The lifting force for a volume of gas is given by the equation: F B = (ρ air - ρ gas) × g × V
The buoyancy compensator is used by ambient pressure divers using underwater breathing apparatus to adjust buoyancy underwater or at the surface within the range of slightly negative to slightly positive, to allow neutral buoyancy to be maintained throughout the depth range of the planned dive, and to compensate for changes in weight due to breathing gas consumption during the dive.
Wing buoyancy compensators generally do not have pockets, as the wing is behind the diver and the harness is usually fairly minimal, but pockets can be added to the waistbelt if there is space. They are supported by the webbing at the top and may be strapped around the thigh to prevent flapping.