The raw material, it appears in the nature in four physical states: solid, liquid, gaseous, and plasma, the particles that form a body in been solid, occupy fixed positions, size and form defined. The liquid and gaseous states do not have fixed form, but they acquire that of the receptacle, which contains them; his particles it can flow, that's why it is called a fluid, as soon as the plasma is constituted by a fluid obtained by means of the finished ionization of a gas, initially neutral, to very high temperatures: his location cannot be realized, with conventional receptacles, but it needs the contests of magnetic fields.
Statics of fluids.
In contrast to the gases, the liquids possess form own in his surfaces free, that in general, it is flat and horizontal bowing lightly in the outskirts of the walls of the receptacle that contains it, forming a hollow or convex meniscus, according to the nature of the liquid and of the material that it constitutes where it is contained, the volume of the liquids changes little with the conditions of pressure and temperature, from what it is said, that they are uncompressible. The gases, due to the big mobility, which has his molecules, are expansibles.
Pressure hydrostatics.
Departing from the pressure as the force, which acts on the surface unit, N/m measures himself ², unit of pascal, where the pressure that exists in the any point of the interior of a liquid, stems from the weight of the liquid, which exists over him. The value of the pressure hydrostatics in a point can be multiplying the distance, that there are even the surfaces well be his depth.
Absolute specific gravity.
In the study of the pressures that exercise the fluids at rest it is necessary to know the thickness or the absolute specific gravity of the fluid, next we have the following relation:
d = m/v; where m is equal to the mass of the substance, v to the volume that it occupies, d the thickness.
But the weight of the substance is (m) (g) = P, where g is the gravity, d.g is considered following = m.g/V, replacing the relation of the weight we have left:
d.g = P/V.
In terms physicist, the absolute specific gravity of a substance, represents the weight of the unit.
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We have the following exercise.
A cylindrical receptacle of radio R = 8cm, contains glycerin of absolute specific gravity p = 1,32/cm ³, up to a height h = 40 cm. What the weight of the glycerin will be in kp.
Information.
R = 8 cm
h = 40 cm
p = 1,32/cm ³
P =?
Solution.
P = p.v
V = base x height
V = pi. R ². h = 3,14 x 64 cm ² x 40 cm
V = 8038,4 cm ³
P = 1,32 p/cm ³ x 8038,4 cm ³
P = 10610,688 p = 10610,688 kp
P = 10610,688 kp
Beginning of pascal.
To explain it, let's consider a point A, in the free surface of a liquid at rest and another point b, in the bosom of the liquid, separated from the first one for the vertical distance h.
Pn = pA p.h, in such a way that it operates on the sucker with a such force that the pressure in A, it is pA p, it is necessary, so that the equation does not alter, the pressure in B, is pn p, this result knows each other with the name of the beginning of pascal and is enunciated of the following way:
Any change of pressure, in a point of a mass flown in balance, is transmitted íntegramente to all the other points, from the fluid mass and to the walls of the receptacle that contains it.
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The beginning of Arquímedes.
An object immersed in a fluid is submitted to a force of direction vertical and felt up, called propulsion, which magnitude is equivalent to the weight of the displaced fluid. An immediate consequence of this floating beginning of the bodies, which can express to themselves if an object floats in a liquid, the weight of the object is equal to the propulsion, which exercises the liquid on the submerged portion of the object.
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Atmospheric pressure.
The ground is surrounded by the ambience, which is a gaseous layer constituted by a gas miscellany, the weight of these gases constitutes the atmospheric pressure, which measures with a few devices so-called barometers, since in the ambience, it is the meteorological stage of the phenomena, factors that determine the atmospheric time they are the temperature, the humid one and the processes adiabáticos, that are the processes that are carried out without heat exchange from the exterior system.
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Paradox hydrostatics.
This paradox alludes in case, where several receptacles of different forms and capacity, which funds have the same areas, where the force, which a liquid exercises on the fund of the receptacle, which contains it is independent from the form and capacity of the receptacle, being equivalent to the weight of the column it liquidates, that it takes the fund of the receptacle as a base and for height the distance between the fund and the level frees of the liquid.
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Finally I think them following, thanks to the study of the mechanics of the fluid, between others are applied very much in the fields of the oceanography for the naval constructions.
In the automotive industry, the beginning of the fluid is applied, so much in the direction, the brakes, to guarantee more safety and better mechanical functionality, in the optimalización of the use of hydrocarbons.
Also we have it in: the hydraulic press, the cat, the brake, the elevator and the crane.
The beginning of Arquímedes is important in field of the statics of fluids, in the naval navigation and the manufacture of vessels.
Bibliographical consulted references.
WHITE, F. “ Mechanics of fluids ' Ed. McGraw Hill (2008).
CURL, A. “ Mechanics of fluids ” Ed. Thomson (2006).
POTTER RIPOLL, A., PÉREZ-SABORID SÁNCHEZ-SHEPHERD, M. " Essentials and applications of the Mechanics of Fluids " Ed. McGraw Hill (2005).
LÓPEZ-HERRERA SÁNCHEZ, J. M., SHOD GUTIÉRREZ, M. A., PÉREZ-SABORID SANCHEZ-SHEPHERD, M., POTTER RIPOLL, A. “ Mechanics of fluids: decisive problems ” Ed. McGraw Hill (2005).
ROCK VILA, R. “ Introduction to the Mechanics of the fluids ' Ed. Limusa (1980).
Bauman R. P., Schwaneberg R. Interpretation of Bernoullís Equation. The Physics Teacher, V-32, November 1994, pp. 478-488.
Bauman R. P: An alternative derivation of Bernoullís principle. Am. J. Phys. 68 (3) March 2000, p. 288-289
Behroozi F., Lambert B. To simple problem in hydrodynamics with to surprising solution. The Physics Teacher Vol 35, May, 1997, pp. 318-319
Behroozi F., Mohazzabi P., McCrickard J. P., Remarkable shapes of to catenary under the effect of gravity and surface tension. Am. J. Phys. 62 (12) December 1994, pp. 1121-1128
Berridge H J J. Radioactive decay chains - to digitalis method. Physics Education. September 1975, pp. 437-438
