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atomic weight
(Encyclopedia)atomic weight, mean (weighted average) of the masses of all the naturally occurring isotopes of a chemical element, as contrasted with atomic mass, which is the mass of any individual isotope. Althoug...blizzard
(Encyclopedia)blizzard, winter storm characterized by high winds, low temperatures, and driving snow; according to the official definition given in 1958 by the U.S. Weather Bureau, the winds must exceed 35 mi (56 k...echo, in acoustics
(Encyclopedia)echo, reflection of a sound wave back to its source in sufficient strength and with a sufficient time lag to be separately distinguished. If a sound wave returns within 1⁄10 sec, the human ear is in...phosphorescence
(Encyclopedia)phosphorescence fŏsˌfərĕsˈəns [key], luminescence produced by certain substances after absorbing radiant energy or other types of energy. Phosphorescence is distinguished from fluorescence in th...Gulf Stream
(Encyclopedia)Gulf Stream, warm ocean current of the N Atlantic Ocean, off E North America. It was first described (1513) by Spanish explorer Ponce de León. The Gulf Stream originates in the Gulf of Mexico and, as...Brownian movement
(Encyclopedia)Brownian movement or motion, zigzag, irregular motion exhibited by minute particles of matter when suspended in a fluid. The effect has been observed in all types of colloidal suspensions (see colloid...malleability
(Encyclopedia)malleability, property of a metal describing the ease with which it can be hammered, forged, pressed, or rolled into thin sheets. Metals vary in this respect; pure gold is the most malleable. Silver, ...McLennan, Sir John Cunningham
(Encyclopedia)McLennan, Sir John Cunningham, 1867–1935, Canadian physicist, grad. Univ. of Toronto (B.A., 1892; Ph.D., 1900). He taught at the Univ. of Toronto from 1892 to 1932, was professor of physics from 190...sintering
(Encyclopedia)sintering, process of forming objects from a metal powder by heating the powder at a temperature below its melting point. In the production of small metal objects it is often not practical to cast the...specific gravity
(Encyclopedia)specific gravity, ratio of the weight of a given volume of a substance to the weight of an equal volume of some reference substance, or, equivalently, the ratio of the masses of equal volumes of the t...Browse by Subject
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