Each substance is characterized by a number of physical and chemical properties on which it can easily be distinguished. At first sight, this knowledge gained within a school course is far from real life. However, we perceive a set of products and materials just on their distinctive properties: to taste, color, smell, density, solubility, hardness. For an example we will consider such recognizable substances as glucose and citric acid.
The underground waters located on a constant aquifer are called ground. They are formed of an atmospheric precipitation, waters of the rivers, lakes, reservoirs and also from inflow of moisture from the surface of the soil. At construction of the hydraulic engineering construction, for example, when digging wells, it is required to determine depth of a proleganiye of ground waters. It is possible to make it in several ways.
There is such expression "fish looks for where is deeper, and the person – where it is better", this very exact reflection of fishing process. Therefore fans of fishing for the greatest success need to learn to determine depth of a reservoir and the nature of a relief of a bottom.
Production of building constructions and metal details requires ability to build pyramid model. In the basis of any pyramid the triangle or a square lies more often, and as side sides serve triangles. The pyramid is carried to polyhedrons. At the truncated pyramid as sides serve trapezes. As well as the usual pyramid truncated is triangular or quadrangular.
The Damask steel – the many-sided, elastic, solid, strong and durable material allowing to achieve to smiths of improbable effects and to realize even the most refined desires at production of a blade or knife. How to make the Damask steel independently and what should be known at the same time?