Recent Examples on the Web: Noun The longer the discussions drag on, the greater the pressure on the companies to secure a deal. Uber, Lyft and others are scrambling for a compromise," 23 June Xi wants to remind the U. Baldor, BostonGlobe. Vincent Ferrer Vikings win league title," 20 June The Democrat, who is at odds with Republican legislative leaders over the next state budget, called on educators to help pressure lawmakers to back her education plan.
Gretchen Whitmer, teachers rally for K funding boost at Capitol," 18 June Conservatives successfully recalled two Democratic state lawmakers in for their votes on gun control measures and pressured another into resigning. Tom Sullivan," 11 June The government too, has learned from this, pressuring Turkish contractors Yapi Merkezi in the Awash-Weldiya rail project much harder on capacity building for ERC engineers and construction staff. Heidi Heitkamp, West Virginia Sen.
Joe Manchin and Indiana Sen. Hawkins, The Verge , "Uber Lite is a slimmed down, 5MB version of the app for emerging markets," 12 June If students finish treatment and go back to their old school or another traditional high school, they may be pressured by other students to return to old habits, Durchslag said. First Known Use of pressure Noun 14th century, in the meaning defined at sense 1a Verb , in the meaning defined at sense 1. History and Etymology for pressure Noun Middle English, from Anglo-French, from Late Latin pressura , from Latin, action of pressing, pressure, from pressus , past participle of premere.
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Resources for pressure Time Traveler! Explore the year a word first appeared. Dictionary Entries near pressure press time press-up pressural pressure pressure accumulator pressure altimeter pressure altitude. Phrases Related to pressure peer pressure take the pressure off tire pressure under pressure water pressure.
Time Traveler for pressure The first known use of pressure was in the 14th century See more words from the same century. Kids Definition of pressure. Comments on pressure What made you want to look up pressure?
Get Word of the Day daily email! With any incremental increase in that temperature, the vapor pressure becomes sufficient to overcome atmospheric pressure and lift the liquid to form vapour bubbles inside the bulk of the substance. Bubble formation deeper in the liquid requires a higher pressure, and therefore higher temperature, because the fluid pressure increases above the atmospheric pressure as the depth increases.
The vapor pressure that a single component in a mixture contributes to the total pressure in the system is called partial vapor pressure. When a person swims under the water, water pressure is felt acting on the person's eardrums. The deeper that person swims, the greater the pressure.
The pressure felt is due to the weight of the water above the person. As someone swims deeper, there is more water above the person and therefore greater pressure. The pressure a liquid exerts depends on its depth. Liquid pressure also depends on the density of the liquid. If someone was submerged in a liquid more dense than water, the pressure would be correspondingly greater. The pressure due to a liquid in liquid columns of constant density or at a depth within a substance is represented by the following formula:. With the "area" in the numerator and the "area" in the denominator canceling each other out, we are left with.
The pressure a liquid exerts against the sides and bottom of a container depends on the density and the depth of the liquid. If atmospheric pressure is neglected, liquid pressure against the bottom is twice as great at twice the depth; at three times the depth, the liquid pressure is threefold; etc. Or, if the liquid is two or three times as dense, the liquid pressure is correspondingly two or three times as great for any given depth.
Liquids are practically incompressible — that is, their volume can hardly be changed by pressure water volume decreases by only 50 millionths of its original volume for each atmospheric increase in pressure. Thus, except for small changes produced by temperature, the density of a particular liquid is practically the same at all depths.
Atmospheric pressure pressing on the surface of a liquid must be taken into account when trying to discover the total pressure acting on a liquid. When this distinction is important, the term total pressure is used. Otherwise, discussions of liquid pressure refer to pressure without regard to the normally ever-present atmospheric pressure.
Pressure and Pascal's principle (part 1)
It is important to recognize that the pressure does not depend on the amount of liquid present. Volume is not the important factor — depth is. The average water pressure acting against a dam depends on the average depth of the water and not on the volume of water held back. If four vases contain different amounts of water but are all filled to equal depths, then a fish with its head dunked a few centimetres under the surface will be acted on by water pressure that is the same in any of the vases.
If the fish swims a few centimetres deeper, the pressure on the fish will increase with depth and be the same no matter which vase the fish is in. If the fish swims to the bottom, the pressure will be greater, but it makes no difference what vase it is in.
All vases are filled to equal depths, so the water pressure is the same at the bottom of each vase, regardless of its shape or volume. If water pressure at the bottom of a vase were greater than water pressure at the bottom of a neighboring vase, the greater pressure would force water sideways and then up the narrower vase to a higher level until the pressures at the bottom were equalized. Pressure is depth dependent, not volume dependent, so there is a reason that water seeks its own level. Restating this as energy equation, the energy per unit volume in an ideal, incompressible liquid is constant throughout its vessel.
At the surface, gravitational potential energy is large but liquid pressure energy is low. At the bottom of the vessel, all the gravitational potential energy is converted to pressure energy.
pressure - Wiktionary
The sum of pressure energy and gravitational potential energy per unit volume is constant throughout the volume of the fluid and the two energy components change linearly with the depth. An experimentally determined fact about liquid pressure is that it is exerted equally in all directions. Because a liquid can flow, this pressure isn't only downward. Pressure is seen acting sideways when water spurts sideways from a leak in the side of an upright can. Pressure also acts upward, as demonstrated when someone tries to push a beach ball beneath the surface of the water.
The bottom of a boat is pushed upward by water pressure buoyancy. When a liquid presses against a surface, there is a net force that is perpendicular to the surface. Although pressure doesn't have a specific direction, force does. A submerged triangular block has water forced against each point from many directions, but components of the force that are not perpendicular to the surface cancel each other out, leaving only a net perpendicular point.
Then it curves downward due to gravity. If there are three holes in a bucket top, bottom, and middle , then the force vectors perpendicular to the inner container surface will increase with increasing depth — that is, a greater pressure at the bottom makes it so that the bottom hole will shoot water out the farthest.
The force exerted by a fluid on a smooth surface is always at right angles to the surface. From Wikipedia, the free encyclopedia. This article is about pressure in the physical sciences. For other uses, see Pressure disambiguation.
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What is pressure?
Entropy and time Entropy and life Brownian ratchet Maxwell's demon Heat death paradox Loschmidt's paradox Synergetics. Caloric theory Theory of heat. Heat ". Thermodynamics Heat engines. Main article: Ideal gas law. Main article: Vapour pressure. Solid mechanics. Fluid mechanics. For instance, over-blowing on a wind instrument can cause an octave rise, which holds as the pressure is reduced. The duct was then replaced and the oscillating pressure measured in similar conditions.
The surprising behaviour of the surfaces of constant total pressure occurs entirely in the boundary layer.
This residue in its turn is then subjected to distillation under reduced pressure to give both a vacuum distillate and a vacuum residue. Possibly, this urban market absorbed part of the area's rural workforce, thereby lightening the pressure on those who sought access to arable land. High pressure studies of energy transfer and strongly coupled bacteriochlorophyll dimers in photosynthetic protein complexes. The right ventricular systolic pressure tends to decrease with age.
Thus, each year the worms were subjected to selection pressure during 2 steps, and to genetic drift during 22 steps. Following a pressure increase in the pipette, the cell suspension was transferred to seminiferous tubules dark blue. The turbulence energy balance is examined, including the separate effects of vertical diffusion of pressure and local kinetic energy. However, escalating divergence of the populations is unlikely in the presence of gene flow unless they experience persistently different selection pressures. The vertical structure of both the wind velocity and pressure fields shows interesting variation along the wave profile.
The basic uncertainty in pressure readings was estimated t o be 0. Need a translator? What is the pronunciation of pressure? My Dictionary. Word of the Day preservation the act of keeping something the same or of preventing it from being damaged. About this. Blog Tangy, tart and fruity: talking about flavours July 03, New Words flat white economy noun July 01, Get our free widgets Add the power of Cambridge Dictionary to your website using our free search box widgets.
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