Fluids react to differences in pressure ; pressure changes are how a fluid is " told " to respond to its environment.

It might appear at first sight as though one connection would serve, but the differences in pressure on which these instruments depend are so minute, that the pressure of the air in the room where the recording part is placed has to be considered.

High inside pressure inhibits motion because the temperature differences are not enough to push the vanes through the higher concentration of air: there is too much air resistance for " eddy currents " to occur, and any slight air movement caused by the temperature difference is damped by the higher pressure before the currents can " wrap around " to the other side.

In measurements of purely mechanical systems ( involving units of length, mass, force, energy, pressure, and so on ), the differences between CGS and SI are straightforward and rather trivial ; the unit-conversion factors are all powers of 10 arising from the relations and.

This direct relationship between curved streamlines and pressure differences was derived from Newton's second law by Leonard Euler in 1754:

The force on the wing can be examined in terms of the pressure differences above and below the wing, which can be related to velocity changes by Bernoulli's principle.

Recent work tries to take into account the roles of differences in parent bodies and the specifics of their orbits, ejection velocities off the solid mass of the core of a comet, radiation pressure from the sun, the Poynting – Robertson effect, and the Yarkovsky effect on the particles of different sizes and rates of rotation to explain differences between meteor showers in terms of being predominantly fireballs or small meteors.

For low pressure differences well above the vapour pressure of water, water is commonly used ( and " inches of water " is a common pressure unit ).

In gauges intended to sense small pressures or pressure differences, or require that an absolute pressure be measured, the gear train and needle may be driven by an enclosed and sealed bellows chamber, called an aneroid, which means " without liquid ".

In addition, there can be differences in pressure due to differences in the elevation ( height ) of the fluid.

The pressure engendered by the new development forced the two rival sultanates to settle their differences over possession of Nugaal, and form a united front against their common enemy.

This force manifests itself as pressure differences between the two sides of the sail-there is a region of low pressure on the front side of the sail and a region of high pressure on the back.

The return tube was not for rebreathing, but because the air exhaust needed to be as near as possible to the regulator's second stage diaphragm, to avoid pressure differences, which would cause a free-flow of gas, or extra resistance to breathing, according to the diver's orientation in the water — head-up, head-down, or level.

Once a syrinx has formed, pressure differences along the spine have been proposed to be one mechanism causing fluid movement within the cyst, possibly resulting in damage to the spinal cord.

Curt's fingers put a little more pressure on the trigger of his gun.

With Rod on his way and Matilda visiting with Mrs. Jackson while they searched out familiar names on the face of the cliff, Harmony settled on the edge of the grub box, to ease the pressure of her swollen body on her bone-weary legs, and worried about all that might have happened to Sally.

He was unable to send any more help to his allies on the Continent, and during the next few years many of them, left to resist French pressure unaided, surrendered to the inevitable and made their peace with Philip.

They are putting strong pressure on their police departments to keep order.

`` U.S. pressure on Britain to foster war hysteria over the status of West Berlin has reached its apogee.

This is a common symptom and the cause usually is pressure on the nerve leading to the affected hand.

A truth-revealing crisis erupted in Katanga for a couple of days this month, to be quickly smothered by the high pressure verbal fog that is kept on tap for such emergencies.

Precise pressure-volume-temperature measurements on corrosive gases are dependent on a sensitive yet rugged pressure transducer.

The results of the study, based on collision integrals computed from the latest critically evaluated data on intermolecular forces in air, will be reported in the form of a table of viscosity, thermal conductivity, thermal diffusion, and diffusion coefficients at temperatures of 1,000 to 10,000 Af and of logarithm of pressure in atmospheres from Af to Af times normal density.

As in many other industries, rising costs and intense competition, both domestic and foreign, have exerted increasing pressure on earnings of the textile industry in recent years.

With such a force of manned bombers we could bring enormous pressure to bear on an enemy, and this pressure would be selective and extremely discriminating.

Heart conditions and high blood pressure escape the stresses brought on by oppressive heat.

Figure 3 shows the data on a silicone fluid, labeled 12,500 cps which gave a high positive normal pressure.

The actual pressure was not determined because the pressure was beyond the upper limit of the apparatus on hand.

Just as the pressure exerted by surface tension in a spherical drop is Af and the pressure exerted by surface tension on a cylindrical shape is Af, the pressure exerted by any curved surface is Af, where **yg is the interfacial tension and Af and Af are the two radii of curvature.

The internal energy of an ideal gas depends on temperature only and is independent of pressure or volume.

It was a response to the conflict between political pressure and the moral intuition which resulted in attempts at prediction.

Instead it means that the thinking in which decision issues has the power to determine the morality of the decision, as in this instance the pressure for renewed practical or legislative attention to the constitutional problems the decision had uncovered might have done.

F.S.C. Northrop, in his discussion of The `` Functions And Future Of Poetry '', suggests this: `` One of the things which makes our lives drab and empty and which leaves us, at the end of the day, fatigued and deflated spiritually is the pressure of the taxing, practical, utilitarian concern of common-sense objects.

This magnificent but greatly underestimated book, which bodies forth the very form and pressure of its time as no other comparable creation, has suffered severely from having been written about an historical event -- the Spanish Civil War -- that is still capable of fanning the smoldering fires of old political feuds.

However, the surface temperature gradient can produce erroneous vapor-pressure measurements for the bulk liquid helium unless precautions are taken to isolate the tube ( which passes through the surface to the vapor pressure bulb ) from the liquid helium surface.

It is also possible to utilize a pressure transducer, mounted at the end of a catheter which is inserted into the heart's left ventricle, to indicate the blood pressure in the heart itself.

Several years ago headlines were made by a small radio transmitter capsule which could be swallowed by the patient and which would then radio internal pressure data to external receivers.

Perhaps it was his misfortune, or good fortune, whichever way one looked at it, to belong to the former group, and he was struggling unconsciously to build up pressure in a world which demanded none, which was positively antagonistic to it.

The face of one block contained a hole 1/16'' '' in diameter which led to a manometer for the measurement of the normal pressure.

Two of the fluids showed a high-positive normal pressure when undergoing shear, and two showed small negative pressures which were negligible in comparison with the amount of the positive pressures generated by the other two.

A system had to be used which did not depend upon the feeding of the fluid into the manometer if measurements of the normal pressure were to be made in a reasonable time.

A back pressure was then introduced, and the rise or fall of the material in the manometer indicated which was greater, the normal pressure in the block or the back pressure.

Although the Af calculation is obvious by analogy with that for gravitational field and osmotic pressure, it is interesting to confirm it by a method which can be generalized to include related effects.

This gives Af, which is the pressure.

From this and the force of deformation it should be possible to calculate the elastic energy of deformation which should be equal to the Af calculated from the pressure normal to the shearing face.

Whipple ( 1955 ) extends the effects to include the solar-corpuscular-radiation pressure, which increases both the minimum particle size and the drag.

The radius is calculated from the mass by assuming spheres of density Af except for the smallest particles, which must have a higher mass density to remain in the solar system in the presence of solar-radiation pressure.

For protein identification, fractions from the column were concentrated by pervaporation against a stream of air at 5-degrees-C or by negative pressure dialysis in an apparatus which permitted simultaneous concentration of the protein and dialysis against isotonic saline.