pressure of a rigid body - it is primarily the first enemy builders.Due to the fact that there is pressure solids, some designs can not be implemented in principle.Interestingly, the ancient, on the contrary enjoyed this property, creating a majestic buildings.Pyramid and many other monuments - all this is the result of hard work in creating magnificent masterpieces.Consider what the pressure is relatively solid.
Found in the days of pressure solids formula reads:
P = F / S,
ieforce acting on the pressure surface is subject.
should be noted that in fact, the pressure force of the body is always positive and is valid in both directions.Here operates Newton's first law - the force of action is equal to the force of resistance.Applicable to life - the pressure exerted by the weight of the building, will be identical to its lower layers, and the foundation.Therefore, designers, builders always expect Will the foundation of a building.Of course, this calculation includes other factors (power of the wind - on the roof, groundwater, seismic activity and so forth.).
Why should a person disperse your weight over a larger surface?And then think of a needle or knife.Both have sharp parts, for better penetrating ability.Now remember skiing and track-type tractors.Skiers do not fall into the snow, and tractors have good permeability through the swamps, so they have more contact area - to a lesser imbeddability.This displays the basic formula, showing the pressure of solids - at the same force, but of different sizes, the pressure will be different.It will be inversely proportional to the area.Iethe larger the area, the greater the pressure.And vice versa.
Now back to the builders.Why did they pressure - big headache?It's all in the same area.After all, the durable material, so it is harder.Think of heavy concrete slabs-floors.Of course, nowadays there are a lot of strong and light materials.But it is not all easy.Any construction project is estimated profitability.And if the price of such materials super-high, and estimates for the construction will be large.As a result, a customer does not pull on Finance, or the project will pay off for a long time.But we have already said that the ancients used the pressure of the solids in their favor.
In those days, construction materials are relatively limited in range and quantity.After all, the mining industry was not, and the stone carved by hand.Communication elements such as concrete or mortar was not there.We had to be used instead of mounting pressure solids.The fact is that the greater the pressure, the greater the required strength of material.But on the other hand, it is a great force of friction.And it is known, can make a huge difference.As a result, we find that the hardware was not needed to keep everything on gravity and friction force.
Now imagine how much pressure has a train on rails - 300,000 kPa !!!At a pressure of specialized crawler tractor - 20 kPa.Quite an interesting point, it would seem, the heavy swamp tractor, creates a relatively low ground pressure.This allows him to move around the impassable and wetlands due to the wide tracks.If we speak about the above-mentioned friction, it can be of different types and is defined by the formula:
F = μ × N, [H]
where F - the frictional force [N],
μ - friction coefficient,
N -normal reaction of [H].
pressure force as can be seen, has both positive and negative points.Nature has adapted to this phenomenon.People from the ingeniously simple designs went to the invention of new materials and technologies.Such a phenomenon in nature and have to be reckoned with him.
