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liquefaction

(Encyclopedia)liquefaction, change of a substance from the solid or the gaseous state to the liquid state. Since the different states of matter correspond to different amounts of energy of the molecules making up t...

spontaneous combustion

(Encyclopedia)spontaneous combustion, phenomenon in which a substance unexpectedly bursts into flame without apparent cause. In ordinary combustion, a substance is deliberately heated to its ignition point to make ...

entropy

(Encyclopedia)entropy ĕnˈtrəpē [key], quantity specifying the amount of disorder or randomness in a system bearing energy or information. Originally defined in thermodynamics in terms of heat and temperature, e...

seasons

(Encyclopedia)CE5 The seasons are caused by the tilt of the earth's axis to the plane of its orbit about the sun. The Northern Hemisphere is tilted toward the sun in the summer and receives more direct rays than...

Dewar flask

(Encyclopedia)Dewar flask [for Sir James Dewar], container after which the common thermos bottle is patterned. It consists of two flasks, one placed inside the other, with a vacuum between. The vacuum prevents the ...

shape memory

(Encyclopedia)shape memory, property possessed by certain alloys that allows them to return, when heated, to their original shape after having been deformed. This effect results because, as the alloy is deformed, i...

megapode

(Encyclopedia)megapode mĕgˈəpōdˌ [key], common name for large, stout-bodied, long-tailed, terrestrial, nonmigratory birds comprising six genera in the family Megapodiidae. Members of the family have large, str...

British thermal unit

(Encyclopedia)British thermal unit, abbr. Btu, unit for measuring heat quantity in the customary system of English units of measurement, equal to the amount of heat required to raise the temperature of one pound of...

nuclear reactor

(Encyclopedia)CE5 Power reactor system nuclear reactor, device for producing controlled release of nuclear energy. Reactors can be used for research or for power production. A research reactor is designed to pr...

Stirling engine

(Encyclopedia)Stirling engine, an external combustion reciprocating engine having an enclosed working fluid that is alternately compressed and expanded to operate a piston, thus converting heat from a variety of so...