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aviation

(Encyclopedia)aviation, operation of heavier-than-air aircraft and related activities. Aviation can be conveniently divided into military aviation, air transport, and general aviation. Military aviation includes al...

copper, chemical element

(Encyclopedia)copper, metallic chemical element; symbol Cu [Lat. cuprum=copper]; at. no. 29; at. wt. 63.546; m.p. 1,083.4℃; b.p. 2,567℃; sp. gr. 8.96 at 20℃; valence +1 or +2. Copper and some of its alloys ha...

locomotive

(Encyclopedia)locomotive, vehicle used to pull a train of unpowered railroad cars. Richard Trevithick, a British engineer and inventor, built and operated (1803–4) the first successful steam engine locomotive f...

deafness

(Encyclopedia)deafness, partial or total lack of hearing. It may be present at birth (congenital) or may be acquired at any age thereafter. A person who cannot detect sound at an amplitude of 20 decibels in a frequ...

basketball

(Encyclopedia)basketball, game played generally indoors by two opposing teams of five players each. Basketball was conceived in 1891 by Dr. James Naismith, a physical education instructor at the YMCA college in Spr...

battery, electric

(Encyclopedia)CE5 Lead storage cell: At the lead-dioxide electrode, electrons from the circuit combine with lead dioxide and sulfuric acid to form lead sulfate and water. At the spongy-lead electrode, lead react...

metal

(Encyclopedia)metal, chemical element displaying certain properties by which it is normally distinguished from a nonmetal, notably its metallic luster, the capacity to lose electrons and form a positive ion, and th...

rubber

(Encyclopedia)CE5 Basic molecules in rubber rubber, any solid substance that upon vulcanization becomes elastic; the term includes natural rubber (caoutchouc) and synthetic rubber. The term elastomer is sometim...

bridge, structure

(Encyclopedia)CE5 Bridges bridge, structure built over water or any obstacle or depression to allow the passage of pedestrians or vehicles. See also viaduct. In wartime, where the means of crossing a stream o...

electricity

(Encyclopedia)CE5 Electrical and radio symbols electricity, class of phenomena arising from the existence of charge. The basic unit of charge is that on the proton or electron—the proton's charge is designate...