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单词 pressure
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pressure


pres·sure

P0543400 (prĕsh′ər)n.1. a. The act of pressing.b. The condition of being pressed.2. The application of continuous force by one body on another that it is touching; compression.3. Abbr. P Physics Force applied uniformly over a surface, measured as force per unit area.4. Meteorology Atmospheric pressure.5. a. A compelling or constraining influence, such as persuasion or negative attitudes, on the mind or will: felt pressure to conform; peer-group pressure.b. An influence acting as a source of distress or hardship: economic pressures forcing people to work two jobs.c. Sports Sustained, effective play that puts an opponent at a disadvantage: Defensive pressure forced the quarterback to throw interceptions.d. The condition of being subjected to physical, mental, social, or economic distress: doesn't work well under pressure.6. A physical sensation produced by compression of a part of the body.7. Archaic A mark made by application of force or weight; an impression.tr.v. pres·sured, pres·sur·ing, pres·sures 1. To force or try to force, as by influence or persuasion: The salesman pressured us to buy the car right away.2. To pressurize.3. To pressure-cook.
[Middle English, from Old French, from Latin pressūra, from pressus, past participle of premere, to press; see per- in Indo-European roots.]

pressure

(ˈprɛʃə) n1. the state of pressing or being pressed2. the exertion of force by one body on the surface of another3. a moral force that compels: to bring pressure to bear. 4. an urgent claim or demand or series of urgent claims or demands: to work under pressure. 5. a burdensome condition that is hard to bear: the pressure of grief. 6. (General Physics) the normal force applied to a unit area of a surface, usually measured in pascals (newtons per square metre), millibars, torr, or atmospheres. Symbol: p or P 7. (General Physics) short for atmospheric pressure, blood pressurevb8. (tr) to constrain or compel, as by the application of moral force9. another word for pressurize[C14: from Late Latin pressūra a pressing, from Latin premere to press] ˈpressureless adj

pres•sure

(ˈprɛʃ ər)

n., v. -sured, -sur•ing. n. 1. the exertion of force upon a surface by an object, fluid, etc., in contact with it. 2. Physics. force per unit area. Symbol: P 3. the state of being pressed or compressed. 4. harassment; oppression; stress: the pressures of daily life. 5. a constraining or compelling force or influence: social pressures. 6. urgency, as of affairs or business: He works well under pressure. 7. atmospheric pressure. 8. blood pressure. v.t. 9. to force toward a particular end by exerting a constraining or compelling influence; coerce: They pressured him into accepting. 10. to pressurize. [1350–1400; Middle English (n.) < Latin pressūra. See press1, -ure]

pres·sure

(prĕsh′ər) Continuous force applied to a gas, liquid, or solid by another gas, liquid, or solid. Pressure is expressed as the amount of force applied per unit of area.

pressure


Past participle: pressured
Gerund: pressuring
Imperative
pressure
pressure
Present
I pressure
you pressure
he/she/it pressures
we pressure
you pressure
they pressure
Preterite
I pressured
you pressured
he/she/it pressured
we pressured
you pressured
they pressured
Present Continuous
I am pressuring
you are pressuring
he/she/it is pressuring
we are pressuring
you are pressuring
they are pressuring
Present Perfect
I have pressured
you have pressured
he/she/it has pressured
we have pressured
you have pressured
they have pressured
Past Continuous
I was pressuring
you were pressuring
he/she/it was pressuring
we were pressuring
you were pressuring
they were pressuring
Past Perfect
I had pressured
you had pressured
he/she/it had pressured
we had pressured
you had pressured
they had pressured
Future
I will pressure
you will pressure
he/she/it will pressure
we will pressure
you will pressure
they will pressure
Future Perfect
I will have pressured
you will have pressured
he/she/it will have pressured
we will have pressured
you will have pressured
they will have pressured
Future Continuous
I will be pressuring
you will be pressuring
he/she/it will be pressuring
we will be pressuring
you will be pressuring
they will be pressuring
Present Perfect Continuous
I have been pressuring
you have been pressuring
he/she/it has been pressuring
we have been pressuring
you have been pressuring
they have been pressuring
Future Perfect Continuous
I will have been pressuring
you will have been pressuring
he/she/it will have been pressuring
we will have been pressuring
you will have been pressuring
they will have been pressuring
Past Perfect Continuous
I had been pressuring
you had been pressuring
he/she/it had been pressuring
we had been pressuring
you had been pressuring
they had been pressuring
Conditional
I would pressure
you would pressure
he/she/it would pressure
we would pressure
you would pressure
they would pressure
Past Conditional
I would have pressured
you would have pressured
he/she/it would have pressured
we would have pressured
you would have pressured
they would have pressured

pressure

Force per unit area.
Thesaurus
Noun1.pressure - the force applied to a unit area of surfacepressure - the force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit); "the compressed gas exerts an increased pressure"force per unit area, pressure levelphysical phenomenon - a natural phenomenon involving the physical properties of matter and energyblood pressure - the pressure of the circulating blood against the walls of the blood vessels; results from the systole of the left ventricle of the heart; sometimes measured for a quick evaluation of a person's health; "adult blood pressure is considered normal at 120/80 where the first number is the systolic pressure and the second is the diastolic pressure"gas pressure - the pressure exerted by a gashead - the pressure exerted by a fluid; "a head of steam"hydrostatic head - the pressure at a given point in a liquid measured in terms of the vertical height of a column of the liquid needed to produce the same pressureintraocular pressure, IOP - pressure exerted by the fluids inside the eyeball; regulated by resistance to the outward flow of aqueous humor; "glaucoma can result from increased intraocular pressure"oil pressure - pressure that keeps oil on the moving parts of an internal-combustion engineosmotic pressure - (physical chemistry) the pressure exerted by a solution necessary to prevent osmosis into that solution when it is separated from the pure solvent by a semipermeable membranecorpuscular-radiation pressure, radiation pressure - the minute pressure exerted on a surface normal to the direction of propagation of a waveinstantaneous sound pressure, sound pressure - the difference between the instantaneous pressure at a point in a sound field and the average pressure at that pointsuction - a force over an area produced by a pressure differencevapor pressure, vapour pressure - the pressure exerted by a vapor; often understood to mean saturated vapor pressure (the vapor pressure of a vapor in contact with its liquid form)
2.pressure - a force that compels; "the public brought pressure to bear on the government"force - a powerful effect or influence; "the force of his eloquence easily persuaded them"
3.pressure - the act of pressingpressure - the act of pressing; the exertion of pressure; "he gave the button a press"; "he used pressure to stop the bleeding"; "at the pressing of a button"pressing, presspush, pushing - the act of applying force in order to move something away; "he gave the door a hard push"; "the pushing is good exercise"impression - the act of pressing one thing on or into the surface of another; "he watched the impression of the seal on the hot wax"compressing, compression - applying pressure
4.pressure - the state of demanding notice or attention; "the insistence of their hunger"; "the press of business matters"imperativeness, insistency, press, insistenceurgency - the state of being urgent; an earnest and insistent necessity
5.pressure - the somatic sensation that results from applying force to an area of skin; "the sensitivity of his skin to pressure and temperature was normal"pressure sensationsomaesthesia, somatesthesia, somatic sensation, somesthesia - the perception of tactual or proprioceptive or gut sensations; "he relied on somesthesia to warn him of pressure changes"
6.pressure - an oppressive condition of physical or mental or social or economic distressdistress - a state of adversity (danger or affliction or need); "a ship in distress"; "she was the classic maiden in distress"
7.pressure - the pressure exerted by the atmospherepressure - the pressure exerted by the atmosphereair pressure, atmospheric pressuregas pressure - the pressure exerted by a gasbarometric pressure - atmospheric pressure as indicated by a barometercompartment pressure - the air pressure maintained in an air-tight compartment (as in an aircraft)overpressure - a transient air pressure greater than the surrounding atmospheric pressure; "the overpressure of the blast kills by lethal concussion"sea-level pressure - the atmospheric pressure reduced by a formula to the pressure at sea level
Verb1.pressure - to cause to do through pressure or necessity, by physical, moral or intellectual means :"She forced him to take a job in the city"; "He squeezed her for information"coerce, force, hale, squeezeturn up the heat, turn up the pressure - apply great or increased pressure; "The Democrats turned up the heat on their candidate to concede the election"drive - to compel or force or urge relentlessly or exert coercive pressure on, or motivate strongly; "She is driven by her passion"bludgeon - overcome or coerce as if by using a heavy club; "The teacher bludgeoned the students into learning the math formulas"steamroll, steamroller - bring to a specified state by overwhelming force or pressure; "The Senator steamrollered the bill to defeat"squeeze for - squeeze someone for money, information, etc.dragoon, railroad, sandbag - compel by coercion, threats, or crude means; "They sandbagged him to make dinner for everyone"terrorise, terrorize - coerce by violence or with threatscompel, obligate, oblige - force somebody to do something; "We compel all students to fill out this form"bring oneself - cause to undertake a certain action, usually used in the negative; "He could not bring himself to call his parents"
2.pressure - exert pressure on someone through threatsblackjack, blackmailact upon, influence, work - have and exert influence or effect; "The artist's work influenced the young painter"; "She worked on her friends to support the political candidate"

pressure

noun1. force, crushing, squeezing, compressing, weight, compression, heaviness The pressure of his fingers had relaxed.2. power, influence, force, obligation, constraint, sway, compulsion, coercion He may be putting pressure on her to agree.3. stress, demands, difficulty, strain, press, heat, load, burden, distress, hurry, urgency, hassle (informal), uphill (S. African), adversity, affliction, exigency The pressures of modern life are great.verb1. force, influence, persuade, compel, intimidate, drive, badger, coerce, bulldoze, brainwash, dragoon, pressurize, breathe down someone's neck, browbeat, press-gang, prevail on, twist someone's arm (informal), turn on the heat (informal), put the screws on (slang) He claimed the police pressured him to change his testimony.Quotations
"If you can't stand the heat, get out of the kitchen" [Harry S. Truman]

pressure

noun1. The act, condition, or effect of exerting force on someone or something:strain, stress, tension.2. Power used to overcome resistance:coercion, compulsion, constraint, duress, force, strength, violence.verb1. To cause (a person or thing) to act or move in spite of resistance:coerce, compel, constrain, force, make, obligate, oblige.2. To maintain normal air pressure in:pressurize.
Translations
压力强制力施加压力极力劝导紧迫

pressure

(ˈpreʃə) noun1. (the amount of force exerted by) the action of pressing. to apply pressure to a cut to stop bleeding; A barometer measures atmospheric pressure. 壓力 压力2. (a) strain or stress. The pressures of her work are sometimes too much for her. 緊迫，壓力 紧迫，压力 3. strong persuasion; compulsion or force. He agreed under pressure. 極力勸導，強制力 极力劝导，强制力 ˈpressurize, ˈpressurise verb1. to fit (an aeroplane etc) with a device that keeps air pressure normal. The cabins have all been pressurized (給飛機等)裝設保持正常氣壓的裝置 （给飞机等）装设保持正常气压的装置 2. to force. He was pressurized into giving up his job. 強迫 强迫pressure cooker a type of saucepan in which food is cooked quickly by steam kept under great pressure. 壓力鍋 压力锅

pressure

→ 压力zhCN, 施加压力zhCN
  • What should the tire pressure be? (US)
    What should the tyre pressure be? (UK) → 轮胎压力应该是多少？

pressure


accede to pressure

To bow down or yield to pressure from an outside force, especially as regards a political, business, or military action or decision. Congress was forced to accede to pressure from the public and abandon its proposal to increase taxes.See also: accede, pressure

no pressure

Said ironically to emphasize that what is being discussed carries a large amount of importance or makes one feel that one must try very hard to succeed. A: "I don't want you to feel intimidated, but this employee review will have a huge bearing on whether or not you're kept on at the end of the year." B: "Wow, no pressure or anything!"See also: no, pressure

yield to pressure

To give into outside forces urging someone to do something. Sally wasn't even going to apply for that boring job, but she yielded to pressure from her mother and submitted her resume nonetheless.See also: pressure, yield

put pressure on (one)

To try to influence or persuade one to do something or act a certain way; to make demands on or expect something from someone. A number of companies have been putting pressure on politicians to ease up on corporate taxes and regulations. My parents have been putting pressure on me to get a job.See also: on, pressure, put

push off

1. Literally, to push against a dock in order to move one's boat away from shore. I'll need you to push off while I steer the boat.2. By extension, to leave or depart. We both need to be up early tomorrow, so we'll be pushing off soon.3. In some sports, to push another player in order to propel oneself away and create more distance from them, typically in order to get "open" to receive a pass, etc. Such a maneuver is typically against the rules. You can clearly see in the replay that Williams pushed off. The refs missed that one.See also: off, push

under pressure

1. Literally, forced through or into some vessel with great compressive force. The contents of this container are under pressure, so do no pierce it or expose it to fire or you could risk triggering an explosion. Crude oil underneath the ground can be under intense pressure, which is why it can erupt into a geyser when drilled into directly.2. (While) facing or enduring a great amount of stress caused by some compelling or constraining influence. I can't talk now, I'm under pressure to get this done before the end of the day! Sorry, I'm just under so much pressure at work that it's made me rather irritable.See also: pressure

pressure (one) into (doing something)

To try to force, influence, or persuade one to do something or act a certain way. A number of corporations have been pressuring politicians into rolling back the strict regulations implemented by the previous administration. My parents pressured me into getting a job since I decided not to go to college.See also: pressure

take (one's) blood pressure

To measure one's blood pressure. I'll need to take your blood pressure before we begin. The doctor told me to take my blood pressure twice a day to see if there was any adverse reaction to the medication.See also: blood, pressure, take

check (one's) blood pressure

To measure one's blood pressure. I'll need to check your blood pressure before we begin. The doctor told me to check my blood pressure twice a day to see if there was any adverse reaction to the medication.See also: blood, check, pressure

high-pressure (one) into (doing something)

To make a great effort to try to force, influence, or persuade one to do something or act a certain way. A number of corporations have been high-pressuring politicians into rolling back the strict regulations implemented by the previous administration. My parents high-pressured me into getting a job since I decided not to go to college.

high-pressure someone into something

Fig. to urge someone forcefully to do something. Here comes Jill. Watch out. She will try to high-pressure you into working on her committee. You can't high-pressure me into doing anything! I'm too busy!

pressure someone into something

to force someone into doing something. Please don't try to pressure me into taking that promotion. You can't pressure me into it. I won't do it!See also: pressure

push off

 and shove offto leave. (As if one were pushing a boat away from a dock.) Well, it looks like it's time to push off. It's time to go. Let's shove off.See also: off, push

push (oneself) off (on something)

[for someone in a boat] to apply pressure to something on the shore, thus propelling the boat and oneself away. The weekend sailor pushed himself off on the boat he had been moored to. We pushed off on the dock.See also: off, push

push someone or something off (of) someone or something

 and push someone or something offto apply pressure to and force someone or something off someone or something. (Of is usually retained before pronouns.) He continued to come at me, but I managed to push him off me and escape. I pushed off the attacker.See also: off, push

put pressure on something

to apply weight or pressure to something. (See also (the) pressure on someone (to do something)">put (the) pressure on someone (to do something).) Put pressure on the wound to stop the bleeding. Put some pressure on the papers to flatten them out.See also: on, pressure, put

put (the) pressure on someone (to do something)

to make demands on someone; to try to get someone to do something. Please don't put pressure on me to go there! We put the pressure on him to get him to come, but he refused.See also: on, pressure, put

take someone's blood pressure

to measure a person's blood pressure. The doctor takes my blood pressure every time I am in the office. Bob takes his blood pressure at home every day.See also: blood, pressure, take

*under pressure

 1. and *under a deadline; *under the gun (about something) Fig. facing or enduring something such as pressure or a deadline. (*Typically: be ~; get ~.) I have to get back to work. I am under a deadline. I am under a lot of pressure lately. The management is under the gun for the mistakes made last year. 2. [of a gas or liquid] being forced, squeezed, or compressed. (*Typically: be ~; deliver something ~; put something ~.) The gas in the pipes leading to the oven are under pressure.See also: pressure

push off

Also, shove off. Leave, set out, depart, as in The patrol pushed off before dawn, or It's time to shove off. This usage alludes to the literal meaning of a person in a boat pushing against the bank or dock to move away from the shore. [Colloquial; early 1900s] See also: off, push

put ˈpressure on somebody (to do something)

,

bring pressure to ˈbear (on somebody) (to do something)

force or try to persuade somebody to do something: The landlord is putting pressure on us to move out. ♢ If the management won’t listen, we’ll have to bring some more pressure to bear.See also: on, pressure, put, somebody

under ˈpressure


1 if a liquid or a gas is kept under pressure, it is forced into a container so that when the container is opened, the liquid or gas escapes quickly
2 being forced to do something: The director is under increasing pressure to resign.
3 made to feel anxious about something you have to do: The team performs well under pressure.See also: pressure

push off

v.1. To shove or thrust something or someone from a place: She climbed up to the roof and pushed off the snow. He pushed a glass off the table, and it shattered.2. To set out; depart: The infantry patrol pushed off before dawn.3. To launch or move away by pushing against a surface: I can jump higher when I push off the ground with my left foot. We got in the boat and pushed off from the dock.See also: off, push

pressure


pressure,

in mechanics, ratio of the forceforce,
commonly, a "push" or "pull," more properly defined in physics as a quantity that changes the motion, size, or shape of a body. Force is a vector quantity, having both magnitude and direction.
..... Click the link for more information.  acting on a surface to the area of the surface; it is thus distinct from the total force acting on a surface. A force can be applied to and sustained by a single point on a solid. However, a force can only be sustained by the surface of an enclosed fluid, i.e., a liquid or a gas. Thus it is more convenient to describe the forces acting on and within fluids in terms of pressure. Units of pressure are frequently force units divided by area units, e.g., pounds per square inch, dynes per square centimeter, or newtons (N) per square meter.

Pressure of Fluids

A fluid exerts a pressure on all bodies immersed in it. For a fluid at rest the difference in pressure between two points in it depends only upon the density of the fluid and the difference in depth between the two points. For example, a swimmer diving down in a lake can easily observe an increase in pressure with depth. For each meter (foot) increase in depth, the swimmer is subjected to an increase in pressure of 9,810 N per sq m (62.4 lb per sq ft), because water weighs 9,810 N per cu m (62.4 lb per cu ft). Since a liquid is nearly incompressible, its density does not change significantly with increasing depth. Therefore, the increase in pressure is caused solely by the increase in depth.

The variations in pressure of a gas are more complicated. For example, since air has such a low density compared to a liquid, a change in its pressure is only measurable between points that have a great height difference. The air pressure in a typical room is the same everywhere, but it is noticeably lower at the top of a mountain than at sea level. Because air is a gas, it is compressible. Its density decreases with increasing altitude. Thus changes in air pressure depend upon both the variations in the density of air and changes in the altitude at which it is measured. These two factors combine to reduce the air pressure at an altitude of 5,500 m (18,000 ft) to one half its value at sea level. Atmospheric (air) pressure at sea level will support a column of mercury that is about 76 cm (30 in.) high. The exact height varies with the weather. A unit called a standard atmosphere exerts a pressure equivalent to a column of mercury 76 cm high at sea level when the temperature is 0&degC;; it is equal to 101,300 N per sq m (14.7 lb per sq in.).

Influences on and Effects of Pressure

Different gas lawsgas laws,
physical laws describing the behavior of a gas under various conditions of pressure, volume, and temperature. Experimental results indicate that all real gases behave in approximately the same manner, having their volume reduced by about the same proportion of the
..... Click the link for more information.  relate the pressure of a gas to its volume, its temperature, or both. A rise in pressure affects both the melting pointmelting point,
temperature at which a substance changes its state from solid to liquid. Under standard atmospheric pressure different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and can be used
..... Click the link for more information.  and the boiling pointboiling point,
temperature at which a substance changes its state from liquid to gas. A stricter definition of boiling point is the temperature at which the liquid and vapor (gas) phases of a substance can exist in equilibrium.
..... Click the link for more information.  of a substance, raising the melting and boiling points of most substances. In the case of water, however, an increase in pressure lowers its melting point so that the pressure of a skate blade on an ice surface causes the ice below it to be converted to the liquid state (see states of matterstates of matter,
forms of matter differing in several properties because of differences in the motions and forces of the molecules (or atoms, ions, or elementary particles) of which they are composed.
..... Click the link for more information. ; expansionexpansion,
in physics, increase in volume resulting from an increase in temperature. Contraction is the reverse process. When heat is applied to a body, the rate of vibration and the distances between the molecules composing it are increased and, hence, the space occupied by the
..... Click the link for more information. ). Bernoulli's principleBernoulli's principle,
physical principle formulated by Daniel Bernoulli that states that as the speed of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases.
..... Click the link for more information.  relates the effect of the velocity of a fluid on the pressure within the fluid.

Buoyancy

A body immersed in a fluid experiences a larger upward pressure on its lower surface than a downward pressure on its upper surface because of the difference in height or depth between the two surfaces; this difference in pressure results in a buoyant force that pushes the body upward (see Archimedes' principleArchimedes' principle,
principle that states that a body immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid. The principle applies to both floating and submerged bodies and to all fluids, i.e., liquids and gases.
..... Click the link for more information. ). If the weight of the body is less than the buoyant force, the body will rise; if the weight is greater, the body will sink. The buoyant effect of this pressure may be noted in the rise of balloons or other objects filled with gases, such as hydrogen or helium, that are less dense than air.

Hydraulic Force

According to Pascal's lawPascal's law
[for Blaise Pascal], states that pressure applied to a confined fluid at any point is transmitted undiminished throughout the fluid in all directions and acts upon every part of the confining vessel at right angles to its interior surfaces and equally upon equal
..... Click the link for more information.  the pressure exerted on an enclosed fluid is transmitted undiminished throughout the fluid and acts equally in all directions. On the basis of this law, various hydraulic devices are used to multiply a force. For example, a force of 10 N exerted on a piston whose area is 1 sq m and which is inserted into an enclosed chamber filled with water or another fluid transmits a pressure of 10 N per sq m throughout the fluid. If a second piston, at another part of the chamber, has an area of 10 sq m, then this pressure results in a force of 10 N being exerted on each square meter of its area, or 100 N total force.

Tools for Measuring Pressure

The instrument for measuring atmospheric pressure, the barometerbarometer
, instrument for measuring atmospheric pressure. It was invented in 1643 by the Italian scientist Evangelista Torricelli, who used a column of water in a tube 34 ft (10.4 m) long.
..... Click the link for more information. , is calibrated to read zero when there is a complete vacuum; the pressure indicated by the instrument is therefore called absolute pressure. The term "pressure gauge" is commonly applied to the other instruments used for measuring pressure. They are manufactured in a great variety of sizes and types and are employed for recording pressures exerted by substances other than air—water, oil, various gases—registering pressures as low as 13.8×103 N per sq m (2 lb per sq in.) or as high as 13.8×107 N per sq m (10 tons per sq in.) and over (as in hydraulic presses). Some pressure gauges are made to carry out special operations, such as the one used on a portable air compressor. In this case, the gauge acts automatically to stop further operation when the pressure has reached a certain point and to start it up again when compression has fallen off to a certain limit.

In general, a gauge consists of a metal tube or diaphragm that becomes distorted when pressure is applied and, by an arrangement of multiplying levers and gears, causes an indicator to register the pressure upon a graduated dial. The Bourdon gauge used to measure steam pressure and vacuum consists essentially of a hollow metal tube closed at one end and bent into a curve, generally elliptic in section. The open end is connected to the boiler. As the pressure inside the tube (from the boiler) increases, the tube tends to straighten out. The closed end is attached to an indicating needle, which registers the extent to which the tube straightens out. For pressure too small to be accurately measured by the Bourdon gauge, the manometer is used. The simplest type of manometer consists of a U tube partially filled with a liquid (i.e., mercury), leaving one end open to the atmosphere and the other end to the source of pressure. If the pressure being measured is greater or less than atmospheric pressure, the liquid in the tube moves accordingly. Pressures up to several million lb per sq in. have been produced in experiments to determine the effect of high pressure on various substances.

Pressure

The ratio of force to area. Atmospheric pressure at the surface of Earth is in the vicinity of 15 lbf/in.2 (1.0 × 105 Pa). Pressures in enclosed containers less than this value are spoken of as vacuum pressures; for example, the vacuum pressure inside a cathode-ray tube is 10-8 mmHg, meaning that the pressure is equal to the pressure that would be produced by a column of mercury, with no force acting above it, that is 10-8 mm high. This is absolute pressure measured above zero pressure as a reference level. Inside a steam boiler, the pressure may be 800 lbf/in.2 (5.5 × 106 Pa) or higher. Such pressure, measured above atmospheric pressure as a reference level, is gage pressure, designated psig. See Pressure measurement

pressure

The force per unit surface area at any point in a gas or liquid. The pressure of a gas is proportional to temperature and density: at constant temperature, as the density is increased the pressure increases accordingly. This law of classical physics does not apply to degenerate matter.

Pressure

 

a physical quantity characterizing the intensity of normal forces (perpendicular to the surface) with which one body acts on another’s surface (for example, the foundations of a building acting on the ground, a liquid acting on the walls of a vessel, and gas in the cylinder of a motor acting on the piston). If the forces are distributed uniformly over the surface, then the pressure ρ on any part of the surface i s p = F/S, where 5 is the area of the part and F is the sum of the forces applied perpendicular to it. If the distribution of forces is nonuniform, this equality gives the mean pressure on the given small area, whereas at the limit, with S tending toward zero, it gives the pressure at a given point. If the distribution of forces is uniform, the pressure at all points of the surface is the same; if the distribution is nonuniform, the pressure varies from point to point.

For a continuous medium, the concept of pressure at each point in the medium is similarly introduced; it plays an important part in the mechanics of liquids and gases. At any point in a quiescent liquid the pressure in all directions is the same;

Table 1. Conversion of units of pressure
 Nlm2barkgflcm2atmmm Hgmm H20
1 N/m2(Pascal).................110-51.01972 x 10-5;0.98692 x 10-5750.06 x 10-50.101972
1 bar = 106dynes/cm2.................10511.019720.98692750.061.01972 x 104
1 kgf/cm2 = 1 at.................0.980665 x 1050.98066510.96784735.56104
1 atm.................1.01325 x 1051.013251.033217601.0332 x 104
1 mm Hg (torr).................133.3221.33322 x 10-31.35951 x 10-31.31579 x10--3113.5951
1 mm H20.................9.806659.80665 x 10-5;10-49.67841 x 10-57.3556 x 10-41

this is true also of moving liquids or gases, if they may be considered ideal (frictionless). In a viscous liquid the value of the mean pressure for three mutually perpendicular directions is taken to be the pressure at a given point.

Pressure plays an important part in physical, chemical, mechanical, and biological phenomena.

S. M. TARG

In a gaseous medium pressure is associated with the transfer of momentum during collisions of thermally moving gas molecules with each other or with the surface of bodies adjacent to the gas. The pressure in gases, which may be called thermal, is proportional to the temperature (the kinetic energy of the particles). In condensed mediums (liquids and solids), unlike gases, in which the mean distances between randomly moving particles are much greater than the size of the particles themselves, interatomic distances are comparable to atomic dimensions and are determined by the equilibrium of interatomic (intermolecular) forces of repulsion and attraction. When atoms approach one another repulsion forces increase, bringing about so-called cold pressure. In condensed mediums the pressure also has a “thermal” component, which is associated with the thermal vibrations of the atoms (nuclei). Given a steady or diminishing volume of a condensed medium, the thermal pressure rises as the temperature increases. At temperatures of about 104 ° K or more, thermal excitation of electrons makes an appreciable contribution to the thermal pressure.

Pressure is measured with manometers, barometers, and vacuometers, as well as with various pressure sensors.

Units of pressure have the dimensions of force divided by area. In the International System of Units, the unit of pressure is the newton per sq m (N/m2); in the Mks system, it is the kilogram-force per sq cm (kgf/cm2). Subsidiary units of pressure also exist—for example, the physical atmosphere (atm), the technical atmosphere (at), the bar, and mm of water and mercury columns (torr), by means of which the pressure measured is compared with the pressure of a column of liquid (water or mercury). (See Table 1.)

In the USA and Great Britain pressure is expressed in pounds-force per square inch (lbf/in.2), poundals per square foot (pdl/ft2), inches of water (in. H20), feet of water (ft H20), and inches of mercury (in. Hg); 1 lbf/in.2 = 6,894.76 N/m2; 1 pdl/ft2 = 1.48816 N/m2; 1 in. H20 = 249.089 N/m2; 1 ft H20 =2,989.07 N/m2; 1 in. Hg = 3,386.39 N/m2.

L. D. LIVSHITS

pressure

[′presh·ər] (mechanics) A type of stress which is exerted uniformly in all directions; its measure is the force exerted per unit area.

pressure

The force per unit area exerted by a homogeneous liquid or gas on the walls of its container.

pressure

1. the normal force applied to a unit area of a surface, usually measured in pascals (newtons per square metre), millibars, torr, or atmospheres. 2. short for atmospheric pressure, blood pressure

pressure


pressure

 (P) [presh´ur] force per unit area.arterial pressure (arterial blood pressure) blood pressure (def. 2).atmospheric pressure the pressure exerted by the atmosphere, usually considered as the downward pressure of air onto a unit of area of the earth's surface; the unit of pressure at sea level is one atmosphere. Pressure decreases with increasing altitude.barometric pressure atmospheric p.blood pressure 1. see blood pressure.2. pressure of blood on walls of any blood vessel.capillary pressure the blood pressure in the capillaries.central venous pressure see central venous pressure.cerebral perfusion pressure the mean arterial pressure minus the intracranial pressure; a measure of the adequacy of cerebral blood flow.cerebrospinal pressure the pressure of the cerebrospinal fluid, normally 100 to 150 mm Hg.continuous positive airway pressure see continuous positive airway pressure.filling pressure see pressure" >mean circulatory filling pressure.high blood pressure hypertension.intracranial pressure see intracranial pressure.intraocular pressure the pressure exerted against the outer coats by the contents of the eyeball.intrapleural pressure (intrathoracic pressure) pleural pressure.intrinsic positive end-expiratory pressure elevated pressure" >positive end-expiratory pressure and dynamic pulmonary hyperinflation caused by insufficient expiratory time or a limitation on expiratory flow. It cannot be routinely measured by a ventilator's pressure monitoring system but is measurable only using an expiratory hold maneuver done by the clinician. Its presence increases the work needed to trigger the ventilator, causes errors in the calculation of pulmonary compliance, may cause hemodynamic compromise, and complicates interpretation of hemodynamic measurements. Called also auto-PEEP and intrinsic PEEP.maximal expiratory pressure maximum expiratory pressure.maximal inspiratory pressure the pressure during inhalation against a completely occluded airway; used to evaluate inspiratory respiratory muscle strength and readiness for weaning from mechanical ventilation. A maximum inspiratory pressure above −25 cm H2O is associated with successful weaning.maximum expiratory pressure (MEP) a measure of the strength of respiratory muscles, obtained by having the patient exhale as strongly as possible against a mouthpiece; the maximum value is near capacity" >total lung capacity.maximum inspiratory pressure (MIP) the inspiratory pressure generated against a completely occluded airway; used to evaluate inspiratory respiratory muscle strength and readiness for weaning from mechanical ventilation. A maximum inspiratory pressure above −25 cm H2O is associated with successful weaning.mean airway pressure the average pressure generated during the respiratory cycle.mean circulatory filling pressure a measure of the average (arterial and venous) pressure necessary to cause filling of the circulation with blood; it varies with blood volume and is directly proportional to the rate of venous return and thus to cardiac output.negative pressure pressure less than that of the atmosphere.oncotic pressure the osmotic pressure of a colloid in solution.osmotic pressure the pressure required to stop osmosis through a semipermeable membrane between a solution and pure solvent; it is proportional to the osmolality of the solution. Symbol π.partial pressure the pressure exerted by each of the constituents of a mixture of gases.peak pressure in mechanical ventilation, the highest pressure that occurs during inhalation.plateau pressure in mechanical ventilation, the pressure measured at the proximal airway during an end-inspiratory pause; a reflection of alveolar pressure.pleural pressure the pressure between the visceral pleura and the thoracic pleura in the pleural cavity. Called also intrapleural or intrathoracic pressure.positive pressure pressure greater than that of the atmosphere.positive end-expiratory pressure (PEEP) a method of control mode ventilation in which positive pressure is maintained during expiration to increase the volume of gas remaining in the lungs at the end of expiration, thus reducing the shunting of blood through the lungs and improving gas exchange. A PEEP higher than the critical closing pressure prevents alveolar collapse and can markedly improve the arterial Po2 in patients with a lowered functional residual capacity, as in acute respiratory failure.Effects of the application of positive end-expiratory pressure (PEEP) on the alveoli. A, Atelectatic alveoli before PEEP application. B, Optimal PEEP application has reinflated alveoli to normal volume. C, Excessive PEEP application overdistends the alveoli and compresses adjacent pulmonary capillaries, creating dead space with its attendant hypercapnia. From Pierce, 1995.pulmonary artery wedge pressure (PAWP) (pulmonary capillary wedge pressure (PCWP)) intravascular pressure, reflecting the left ventricular end diastolic pressure, measured by a swan-ganz catheter wedged into a small pulmonary artery to block the flow from behind.pulse pressure the difference between the systolic and diastolic pressures. If the systolic pressure is 120 mm Hg and the diastolic pressure is 80 mm Hg, the pulse pressure is 40 mm Hg; the normal pulse pressure is between 30 and 40 mm Hg.urethral pressure the pressure inwards exerted by the walls of the urethra, which must be counteracted in order for urine to flow through; see also profile" >urethral pressure profile.venous pressure the blood pressure in the veins; see also central venous pressure" >central venous pressure.water vapor pressure the tension exerted by water vapor molecules, 47 mm Hg at normal body temperature.wedge pressure blood pressure measured by a small catheter wedged into a vessel, occluding it; see also pulmonary capillary wedge pressure and wedged hepatic vein pressure.wedged hepatic vein pressure the venous pressure measured with a catheter wedged into the hepatic vein. The difference between wedged and free hepatic vein pressures is used to locate the site of obstruction in portal hypertension; it is elevated in that due to cirrhosis, but low in cardiac ascites or portal vein thrombosis.

pres·sure (P, P),

(presh'ŭr), 1. A stress or force acting in any direction against resistance. 2. physics, physiology the force per unit area exerted by a gas or liquid against the walls of its container or that would be exerted on a wall immersed at that spot in the middle of a body of fluid:The pressure can be considered either relative to some reference pressure, such as that of the ambient atmosphere (imagined as on the other side of the wall) or in absolute terms (relative to a perfect vacuum). [L. pressura, fr. premo, pp. pressus, to press]

pressure

Vox populi A force or stress applied to a suface by a fluid or object, and measured in units of mass per unit area. See Blood pressure, Continuous positive airway pressure, Coronary perfusion pressure, End-diastolic pressure, End-systolic pressure, Intracranial pressure, Intraocular pressure, Intrauterine pressure, Negative pressure, Negative end-expiratory pressure, Oncotic pressure, Osmotic pressure, PEEP, Pulmonary-capillary pressure, Transpulmonary pressure, Wedge pressure.

pres·sure

(presh'ŭr) 1. A stress or force acting in any direction against resistance. 2. physics, physiology The force per unit area exerted by a gas or liquid against the walls of its container or that would be exerted on a wall immersed at that spot in the middle of a body of fluid. The pressure can be considered either relative to some reference pressure, such as that of the ambient atmosphere (gauge pressure), or relative to a perfect vacuum (absolute pressure). [L. pressura, fr. premo, pp. pressus, to press]

pressure 

The force per unit area exerted by a gas or liquid over a surface in a direction perpendicular to that surface. The SI unit of pressure is the pascal (Pa), although blood pressure and intraocular pressure remain specified in the non-SI unit millimetres of mercury (mmHg). See oxygen permeability.
blood pressure See sphygmomanometer.
equivalent oxygen pressure See equivalent oxygen pressure.
intraocular pressure (IOP) The pressure within the eyeball occurring as a result of the constant formation and drainage of the aqueous humour. This is measured by means of a manometer. What is actually measured in the human eye is the ocular tension by means of a tonometer. This is an indirect measure of the IOP as it depends on the thickness and rigidity of the tunics of the eye besides the IOP. Both terms, intraocular pressure and ocular pressure, are usually regarded as synonymous. Normal IOP is usually considered to be between 11 mmHg and 21 mmHg. However, there may be cases of glaucoma with lower IOP than 21 mmHg and there are also many normal cases with IOP greater than 21 mmHg. There is a slight increase in IOP with age (about 2 mmHg), in the morning as compared to the evening (about 3-4 mmHg), in the supine position as compared to the sitting position (about 3-4 mmHg), and a decrease during accommodation (about 4 mmHg). See in intraocular pressure diurnal variations; glaucoma; aqueous humour; ocular hypertension; ocular hypotony; scleral indentation; Imbert-Fick law; ocular rigidity; differential intraocular pressure test; provocative test; tonometer.
osmotic pressure The pressure required to stop the movement of water through a semipermeable membrane (e.g. corneal endothelium) from one solution of a given concentration to another of a different concentration. When the concentration of the solution on both sides of the membrane is equal, i.e. at equilibrium, the pressure of water on both sides of the membrane will be equal to the osmotic pressure and the movement of water will stop. The more concentrated the solution, the greater the osmotic pressure. See osmosis; hypertonic solution; hypotonic solution; isotonic solution.
pulse pressure See sphygmomanometer.

pres·sure

(P) (presh'ŭr) Stress or force acting in any direction against resistance. [L. pressura, fr. premo, pp. pressus, to press]

Patient discussion about pressure

Q. how can i reduce my blood pressure? A. The main steps in lowering high blood pressure is to take some very important changes in lifestyle- consuming much less salt in food, losing weight and exercising regulary. If this doesn't help (and usually it doesn't help mainly when people don't try hard enought and make an effort), medications can be added to control the blood pressure.

Q. what do i need to do to bring down my blood pressure? what cause a high blood pressure? what are the risks? of high blood pressure ? how can i deal with it effectively ?A. here are two really good sites that show you specifics: http://www.lifeclinic.com/focus/blood/loweringit.asp
http://www.ehow.com/how_12778_eat-lower-blood.html?ref=fuel&utm_source=yahoo&utm_medium=ssp&utm_campaign=yssp_art Hope this helps.

Q. What Are the Complications of High Blood Pressure? My wife suffers from high blood pressure. What are the possible complications that are so dangerous? Why is it important to keep high blood pressure under balance?A. While elevated blood pressure alone is not an illness, it often requires treatment due to its short and long-term effects on many organs. The risk is increased for: Cerebrovascular accident (CVAs or strokes), myocardial infarction (heart attack), hypertensive cardiomyopathy (heart failure due to chronically high blood pressure),hypertensive retinopathy - damage to the retina, hypertensive nephropathy- chronic renal failure due to chronically high blood pressure and hypertensive encephalopathy- confusion, headache and convulsions due to edema in brain that can lead to death. Therefore, it is considered very important to reduce blood pressure to normal levels with strict medical supervision.

More discussions about pressure
AcronymsSeeP

pressure


Related to pressure: hydrostatic pressure, force, blood pressure, air pressure
  • all
  • noun
  • verb

Synonyms for pressure

noun force

Synonyms

  • force
  • crushing
  • squeezing
  • compressing
  • weight
  • compression
  • heaviness

noun power

Synonyms

  • power
  • influence
  • force
  • obligation
  • constraint
  • sway
  • compulsion
  • coercion

noun stress

Synonyms

  • stress
  • demands
  • difficulty
  • strain
  • press
  • heat
  • load
  • burden
  • distress
  • hurry
  • urgency
  • hassle
  • uphill
  • adversity
  • affliction
  • exigency

verb force

Synonyms

  • force
  • influence
  • persuade
  • compel
  • intimidate
  • drive
  • badger
  • coerce
  • bulldoze
  • brainwash
  • dragoon
  • pressurize
  • breathe down someone's neck
  • browbeat
  • press-gang
  • prevail on
  • twist someone's arm
  • turn on the heat
  • put the screws on

Synonyms for pressure

noun the act, condition, or effect of exerting force on someone or something

Synonyms

  • strain
  • stress
  • tension

noun power used to overcome resistance

Synonyms

  • coercion
  • compulsion
  • constraint
  • duress
  • force
  • strength
  • violence

verb to cause (a person or thing) to act or move in spite of resistance

Synonyms

  • coerce
  • compel
  • constrain
  • force
  • make
  • obligate
  • oblige

verb to maintain normal air pressure in

Synonyms

  • pressurize

Synonyms for pressure

noun the force applied to a unit area of surface

Synonyms

  • force per unit area
  • pressure level

Related Words

  • physical phenomenon
  • blood pressure
  • gas pressure
  • head
  • hydrostatic head
  • intraocular pressure
  • IOP
  • oil pressure
  • osmotic pressure
  • corpuscular-radiation pressure
  • radiation pressure
  • instantaneous sound pressure
  • sound pressure
  • suction
  • vapor pressure
  • vapour pressure

noun a force that compels

Related Words

  • force

noun the act of pressing

Synonyms

  • pressing
  • press

Related Words

  • push
  • pushing
  • impression
  • compressing
  • compression

noun the state of demanding notice or attention

Synonyms

  • imperativeness
  • insistency
  • press
  • insistence

Related Words

  • urgency

noun the somatic sensation that results from applying force to an area of skin

Synonyms

  • pressure sensation

Related Words

  • somaesthesia
  • somatesthesia
  • somatic sensation
  • somesthesia

noun an oppressive condition of physical or mental or social or economic distress

Related Words

  • distress

noun the pressure exerted by the atmosphere

Synonyms

  • air pressure
  • atmospheric pressure

Related Words

  • gas pressure
  • barometric pressure
  • compartment pressure
  • overpressure
  • sea-level pressure

verb to cause to do through pressure or necessity, by physical, moral or intellectual means :"She forced him to take a job in the city"

Synonyms

  • coerce
  • force
  • hale
  • squeeze

Related Words

  • turn up the heat
  • turn up the pressure
  • drive
  • bludgeon
  • steamroll
  • steamroller
  • squeeze for
  • dragoon
  • railroad
  • sandbag
  • terrorise
  • terrorize
  • compel
  • obligate
  • oblige
  • bring oneself

verb exert pressure on someone through threats

Synonyms

  • blackjack
  • blackmail

Related Words

  • act upon
  • influence
  • work
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更新时间：2024/9/24 4:17:23