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pressure

(Encyclopedia)pressure, in mechanics, ratio of the force 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 si...

pressure group

(Encyclopedia)pressure group, body, organized or unorganized, that actively seeks to promote its particular interests within a society by exerting pressure on public officials and agencies. Pressure groups direct t...

vapor pressure

(Encyclopedia)vapor pressure, pressure exerted by a vapor that is in equilibrium with its liquid. A liquid standing in a sealed beaker is actually a dynamic system: some molecules of the liquid are evaporating to f...

blood pressure

(Encyclopedia)blood pressure, force exerted by the blood upon the walls of the arteries. The pressure in the arteries originates in the pumping action of the heart, and pressure waves can be felt at the wrist and a...

pressure-treated wood

(Encyclopedia)pressure-treated wood, wood that has had a liquid preservative forced into it in order to protect against deterioration due to rot or insect attack. The most commonly used preservatives are chromated ...

decompression sickness

(Encyclopedia)decompression sickness, physiological disorder caused by a rapid decrease in atmospheric pressure, resulting in the release of nitrogen bubbles into the body tissues. It is also known as caisson disea...

isobar

(Encyclopedia)isobar īˌsəbărˈĭk [key], line drawn on a weather map through points of equal atmospheric pressure. Isobars are used to define cyclones (low-pressure regions) and anticyclones (high-pressure regi...

barograph

(Encyclopedia)barograph, instrument used to make a continuous recording of atmospheric pressure. The pressure-sensitive element, a partially evacuated metal cylinder, is linked to a pen arm in such a way that the v...

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