Before we talk about the properties of water, it is necessary to deal with the concept of "water."It is a clear liquid, which in most cases has no characteristic color or odor.When the water passes into another physical state, it forms derivatives which are referred to as ice, snow (solid state) or the vapor (gaseous).It is believed that it covers more than 70% of the surface of planet Earth - it's all kinds of seas and oceans, rivers, lakes, glaciers and other hydrological facilities.
Water is a strong solvent, which under natural conditions comprises a plurality of mineral salts and various gases.If we talk about its physical properties, then immediately turn our attention to the fact that the melting of the ice increases its density, while at the other substances similar process is exactly the opposite.
main feature is the viscosity of water.By itself, the strength - the ability of any substance (whether liquid, gas or solid body) to provide resistance during movement of particulate material with respect to each other.This feature can be of two types - bulk and tangential.Bulk viscosity - is the ability of a substance to make the tensile force.It manifests itself in the propagation of sound in water, or ultrasonic waves.Tangential viscosity fluid characterized by the ability to resist shear.
When the researchers examined the viscosity of water, it was found that the resistance of the material when stretching and shifts depends on the speed of motion of particles of different layers of liquid.If the layer which moves faster acting on the layer, moving slowly, the effect is the accelerating force.If everything is exactly the opposite, it begins to operate the braking force.The above forces are directed tangentially to the surfaces of the layers.
According to Newton's law was a formula τ = μ dυ / dn, according to which the internal friction force is proportional to the velocity gradient along the normal and the area of impact.If the frictional force attributed to the area of which is equal to unity, then we obtain the shearing stress in the liquid that is indicated in the above formula.
There is also such a thing as the kinematic viscosity of water.He is the ratio of the dynamic coefficient (μ) to the density of the selected liquid (ρ).As an expression of this formula will be as follows: ν = μ / ρ.
viscosity of water at different temperatures change, that is, the values of its coefficients decrease with increasing temperature.Thus, the dynamic viscosity at the salt water will be slightly different from the ratio of fresh.In calculating the difference of the index will fluctuate roughly within 5%.
can cite several formulas, but it is useless as the main material was described earlier.The viscosity of the water by definition can change, not to mention the physical state of matter.These data are important in aviation and shipbuilding and other industries.
There is a special table for the determination of the viscosity of water at different temperatures.This material can be used not only in theory but also in practice.The table contains data at intervals of 5 degrees, ranging from 5 and ending with 100 degrees, which greatly facilitates the life of teachers and students in the calculations.
Another important indicator - the dynamic kinematic viscosity of water, so-called second viscosity (volume) - a characteristic deformation of volumetric compression.Playing a significant role in reducing the attenuation of sound and shock waves.
