's do a simple experiment: take a slightly inflated rubber ball and "imbedded" in water.If the depth of immersion even be 1-2 meters, it is easy to see that its volume is reduced, ie,on all sides the ball will crimp some force.It is usually said that there are "guilty" hydrostatic pressure - the physical analog of the force acting in the still immersed body fluids.Hydrostatic forces acting on the body from all sides, and their resultant, known as the Archimedes force, also called ejector, which corresponds to the direction of its effect on the body immersed in a fluid.
Archimedes discovered his law purely experimental, and its theoretical justification waited for nearly 2,000 years before Pascal discovered the law of hydrostatics for stationary liquid.According to this law, the pressure transmitted through the fluid in all directions regardless of the area on which it acts on all the planes bounding the liquid, and its magnitude is proportional to P, and the surface S along the normal thereto.Pascal opened and checked on the experience of the law in 1653. According to him, the surface immersed in a liquid body from all sides hydrostatic pressure.
assume that a vessel with water submerged body in the form of cube L on the depth H - distance from water surface to the upper edge.This lower bound is at a depth of H + L.The force vector F1, acting on the upper face is directed downward and F1 = r * g * H * S, where r - the density of the liquid, g - acceleration of gravity.
force vector F2, acting on a lower plane upwards, and its value is given by F2 = r * g * (H + L) * S.
force vectors acting on the lateral surface are mutually balanced, so further excluded from consideration.Buoyancy force F2 & gt;F1 and directed upwards, and is attached to the lower face of the cube.Define its value F:
F = F2 - F1 = r * g * (H + L) * S - r * g * H * S = r * g * L * S
Note that the L * S- V is the volume of a cube, and m. to. * g = r p represents the unit weight of liquid, the buoyancy force formula defines the weight volume of fluid equal to the volume of the cube, i.e.This is precisely the weight of the fluid displaced by the body.Interestingly, talk about Archimedes' principle is only possible to the environment, where there is the force of gravity - in conditions of weightlessness the law is not working.Finally, the law of Archimedes formula is as follows:
F = p * V, where p - the proportion of liquid.
Archimedean force can serve as a basis for the analysis of the buoyancy bodies.The condition for the analysis is the ratio of the weight of a body immersed Pm and Pf with the weight of the liquid volume equal to the volume of liquid in the submerged parts of the body.If Pm = Px, the body floating in the liquid, and if Pm & gt;Pf, the body sinks.Otherwise, the body emerges as the buoyant force is equal to the weight of the ejected recessed part of the body of water.
Law of Archimedes and its use has a long history in the art, starting with the classic example of the use of all known and floating facilities to balloons and airships.It played a role that gas refers to a state of matter that is quite fluid models.Thus, in the air on any objects Archimedes force akin to the same as in the liquid.The first attempts to carry out air balloon flight took Montgolfier brothers - they filled a balloon with warm smoke, so that the weight of a prisoner in a ball of air was less than the weight of the same volume of cold air.This was the cause of the lift, and its value is determined as the difference in weight of two volumes.A further improvement of the balloons was burner which continuously heats the air inside the ball.It is understood that the range dependent on the length of the burner.Later in airships used for filling a gas with a specific gravity less than that of air.
