The entire mass of the air component of the atmosphere has his weight on the ground a certain pressure, which is called atmospheric pressure. Atmospheric (barometric) pressure of 1 atm. Is called normal. In technology and in the diving business for a unit of pressure more likely to take the pressure force of 1 kg per 1 cm2 of surface. This unit of pressure is called technical atmosphere and represent atm (1 atm = 1 kg/cm2, which corresponds to 1 ohm water. Art., Or 735.6 mm Hg. Art. Or 0.968 atm.).
Atmospheric pressure affects not only the surface of the earth; it also acts on the surface of the body. A simple calculation shows that the air pressure on the human body, whose surface is about 1.5-2 m 2, is about 15-20 m. At first glance, it appears that such pressure should flatten man. And yet people do not feel that pressure. The fact that the human body consists of 65-70% liquid and the liquid is known to be virtually incompressible. Furthermore, in humans there is' a series of pneumatic cavities (lungs, stomach and intestines, the middle ear cavity), in which the air pressure equal to atmospheric pressure, so external air pressure is balanced by the same pressure from the inside. But if you pump the air out of the respiratory cavities, people immediately feel the full weight of the air column.
The body of an athlete being in the water, experiencing not only the pressure of the weight of a column of air (atmospheric pressure), but also pressure from the weight of the water column. Since the pressure above atmospheric pressure is excessive, then the pressure exerted on the body only from the action of water, called excessive. The amount of pressure and atmospheric pressure (otherwise pressure measured from zero-full vacuum) is the absolute pressure. Gauge and absolute pressure is usually measured in technical atmospheres (atm), which for convenience are denoted by: TAE (technical atmosphere excess) and AAT (atmosphere absolute technical).
This pressure will correspond to the excess pressure 6 atm, or 60 m of water. Art. |
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