As already mentioned, the pressure literally surrounds us.It exists in either the subject or organism.Suffice it to say that any object or living being on the Earth's surface, pressing pressure of 100 kN / m2.The pressure of the air column.People once more perceive visual picture pressure as directed forces in an enclosed volume.This is true for isolated vessels.In open vessels this picture - a consequence of the pressure column.Any pressure in the fluid and gas - is the result of the "behavior" of the molecules of the material.Absolutely true for liquid, gas and solid approval of the pressure as the physical quantity - a total force of blows all the molecules of the surface.
From elementary physics course known that formula-pressure fluid and gas is of the form:
P = ρ × g × h, [Pa]
consider where such components.If you take any amount of liquid / gas, determine the pressure in the area it is possible as follows.Pressure - a force applied to the area - F / S.It is clear to any student.Now write out what the force of Newton's second law - body mass times acceleration (in this case - when the working fluid in a state of mind - the acceleration of gravity).In turn, the weight - is the product density on the volume occupied by the body.The volume can be decomposed as the product of the area to the height.In formula form we get:
P = F / S = (m × g) / S = (V × ρ × g) / S = (S × h × ρ × g) / S = ρ × g × h
where P - pressure, F - force, S - pdoschad, m - weight, g - gravitational acceleration, V - volume, ρ - density, h - height
Pa = N / m2 = (kg × m / s2) / m2 = (m3 × kg / m3 × m / s2) / m2 = (m2 × m × kg / m3 × m / s2) / m2 = m × kg / m3 × m / s2 = kg / (m × c2)
These units show as a way of Pascal.Blaise Pascal was a renowned scholar, including those in the field of physics.He is the author of the basic law, which answers the question: "How to find the pressure of the gas or liquid when it is at rest?"On the basis of his experience was obtained by one of the fundamental laws of physics and hydraulic - pressure of the body (liquid or gas) at any selected point equally over the whole surface, which interacts with the body.
more modern science - Hydraulics is armed and the law, with its authorship - "The law of constant pressure."It states that the fluid pressure is constant at any point of the liquid, provided it rest.These are the basics, and laid the foundation for the calculations of complex systems, and now made it possible to create unusual solutions.Nowadays, any system or mechanism that works with a liquid or gas, without fail calculated on exceeding of limit values (which are known from the experiments for different materials) which form a pressure in the liquid and gas.
If we consider the pressure with a calm state of liquid, you should talk about gidrostaticheskome pressure.If we are the dynamics, it is more relevant to talk about the surge.Water hammer - a phenomenon that occurs in tanks and pipes, due to a sharp increase in pressure in any location.All gidromehanizmy and their elements are calculated to limit the static pressure and short casts - hammering.For example, a common cause of failure of the water taps is just hammer.The big jump in the line trunk can reach the tap, and it fails (wholly or partly).
Curiously, though, and incompressible fluid (almost) on the one hand, it improves the transmission pulse.On the other - if the path will be long and it will be interference (for example, household filters), the hammer can completely extinguish.Change in pressure of liquid and gas, and other possible factors.The first thing that comes from the formula - a change in the height of the container.This principle is actively used in ancient times, different civilizations, as well as can be clearly seen in the villages.Still left over from the Soviet Union water towers operate on this principle.The large capacity pressure injection pump supplied water to a certain level.It is controlled automatically - float in your toilet cistern (when the level of the float rises and the lever shuts off the water).Further, self-feed liquid flows, asabove the ground level of large and small hole.
addition, the pressure can be changed by changing the temperature.It affects the velocity of the molecules, and thus the number of strokes.It would seem that the larger it is, the greater will be the pressure in the liquid and gas.But is it?Not really.All that matters in the properties.Water, for example, thicken and increase in volume, and air - is reduced.A simple example - who has a garden knows that the winter should be drained from the system lines to pipes and valves not burst.Another example on the air - inflate a balloon and place it in the refrigerator for 10 ... 15 minutes.When you you pull it, it will decrease in volume.If you pour it with hot water from the kettle, he quickly swell.
pressure - a phenomenon that we have to not only live, but also to be considered.Think diving to a depth or a sound wave with a strong thunder.Always be careful and remember that the pressure - it is the movement of molecules, and molecules - are small pieces of life!
