Pressure (the symbol: p) is the ratio of force to the area over which that force is distributed. In other words, pressure is force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure (also spelled gage pressure) is the pressure relative to the local atmospheric or ambient pressure. While pressure may be measured in any unit of force divided by any unit of area, the SI unit of pressure (the newton per square metre) is called the pascal (Pa) after the seventeenth-century philosopher and scientist Blaise Pascal. A pressure of 1 Pa is small; it approximately equals the pressure exerted by a dollar bill resting flat on a table. Everyday pressures are often stated in kilopascals (1 kPa = 1000 Pa).

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Famous quotes containing the word pressure:

    By school age, many boys experience pressure to reveal inner feelings as humiliating. They think their mothers are saying to them, “You must be hiding something shameful.” And shucking clams is a snap compared to prying secrets out of a boy who’s decided to “clam up.”
    Ron Taffel (20th century)

    Osteopath—One who argues that all human ills are caused by the pressure of hard bone upon soft tissue. The proof of his theory is to be found in the heads of those who believe it.
    —H.L. (Henry Lewis)

    We believe that civilization has been created under the pressure of the exigencies of life at the cost of satisfaction of the instincts.
    Sigmund Freud (1856–1939)