Buoyancy
The static buoyancy is a force of gravity opposite force on a body in liquids or gases. The static buoyancy is caused by the displacement of the surrounding medium. He causes vessels to swim or fly hot air balloons.
The strength of the buoyancy resulting from the Archimedean principle.
Cause and size of
The source of the lifting force is that the hydrostatic pressure depending on the height of the considered location. On the underside of the body, a higher pressure than on the upper side acts. If no fluid can reach the bottom of the body, then the Archimedean principle does not apply. In this case, there is no buoyancy force.
The static buoyancy corresponds to the weight of the displaced fluid. The fluid may be a liquid such as water or a gas such as air. This relationship is known as Archimedes' principle. A body which is immersed in a fluid with the density, thus acts a lifting force with the amount of:
Here is the displaced volume of fluid from the body. The product is the mass of the displaced fluid from the body. And is its weight.
The hydrostatic paradox indicates that the pressure is dependent only upon the depth and not the form of a fluid. Therefore, the buoyant force is independent of the amount of the fluid in which the body is immersed.
Examples
- Balloons to rise, because they are filled with a carrier gas. The balloon rises if its density is lower than that of the surrounding air. That is, the mass of all components of the balloon, that is the basket, the cover and the gas contained therein, is divided by the total volume must be less than the density of the surrounding air.
- In the natural convection density differences provide for a gravity circulation.
- Ships float on the water because the dipped in the water part of the ship is lighter than the displaced water and the total weight of the vessel corresponds to the total weight of the displaced water from him. Because of the large air spaces a ship despite the heavy materials has a lower average density than water. Floating vessels are in stable equilibrium: If you dive in, then increases the lift and they are lifted up again. Will they lifted up too far, there is a reduction of the buoyancy and gravity allows them to immerse themselves again.
- U- Boats: In static diving ballast tanks are specifically flooded. A submarine can be held in a certain water depth.
- Basement structures are affected by high groundwater levels from the lift. A house with a waterproof basement reinforced concrete can float with rising water. Therefore, these cellars are sometimes deliberately flooded in flooding.
- Scuba divers tare using a buoyancy compensator, which can be filled via the compressed air bottle. Filling the buoyancy compensator results in increased buoyancy (positive buoyancy), the volume of the displaced water is increasing, and the diver rises. Since with decreasing depth further decreases the water pressure, the buoyancy compensator expands further and the diver rises even faster. Not to be driven to the water surface, air must be vented from the BCD again. And the respiration of the compressed air results in a change in volume of the upper body. This effect can also be used on a smaller scale for buoyancy.
Hazard potential
Bearing, unsecured items that can float in water, place it in a flood hazard potential represents a heating oil tank can float in the flooded tank room, tilt, lines can tear and leak. Felled timber, sea containers or swap bodies can have an abortion at elevated water levels and lead by abutting piers, Verklausen ( closing the flow rates ) of bridges and piling of flood protection walls to severe damage.