The human body is made up of fabrics of different specific weight.
. Well-nourished people have a lower specific gravity due to excessive amounts of fat tissue; the proportion is less than one (about 0.94). Man-normal body has negative buoyancy in water of approximately 1 to 1.5 kg (i.e., its own weight will be slightly greater than the weight of displaced water to them).
If the swimmer, lying on the water, will not produce any movement, it begins to sink. However, it is enough to make a full breath and lie on the surface of the water, he will not drown, because when filling the lungs with air chest takes a larger volume and displace more water, this will make the body buoyant, and its average specific gravity becomes less than unity (about 0.96). In this technique often used by swimmers to rest in the supine position. Trained swimmer breathes quietly in this position, without making a complete exhalation, and constantly maintained in the lungs of a slightly larger volume of air than usual.
Depending on the type of equipment in which a person is immersed under water, will change its buoyancy. During the descent in a diving suit, he will have positive buoyancy, and to plunge to the bottom, he must wear a belt with lead weights.
What kind of buoyancy is the most suitable for swimming gear in the water? For large negative buoyancy athlete must exert great effort to stay on the right level, without sinking to the bottom. Large positive buoyancy makes it difficult to dive. It is believed that the most favorable conditions for swimming under water created when a small negative buoyancy (about 0.5-1 kg).
For swimming, the water runs and performs various operations on the ground or under the ship to adjust buoyancy and additional weights, in addition, so put on the body of items of equipment and additional loads to a swimmer could easily maintain the right body position. This ability to hold the water in most comfortable position is called the stability of a swimmer (diver). |
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