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balloon
(Encyclopedia)balloon, lighter-than-air craft without a propulsion system, lifted by inflation of one or more containers with a gas lighter than air or with heated air. During flight, altitude may be gained by disc...internal-combustion engine
(Encyclopedia) CE5 Internal-combustion engines: In the four-stroke reciprocating engine (above), a mixture of fuel and air is taken into the chamber on the down-stroke of the piston, is compressed on the up-strok...ship
(Encyclopedia)ship, large craft in which persons and goods may be conveyed on water. In the U.S. Navy the term boat refers to any vessel that is small enough to be hoisted aboard a ship, and ship is used for any la...airline industry
(Encyclopedia)airline industry, the business of transporting paying passengers and freight by air along regularly scheduled routes, typically by airplanes but also by helicopter. Ferdinand Graf von Zeppelin set up ...transportation
(Encyclopedia)transportation, conveyance of goods and people over land, across water, and through the air. See also commerce. The first practical attempts at air transportation began with the invention of the h...ion, in chemistry
(Encyclopedia)ion, atom or group of atoms having a net electric charge. Ionization has many applications. Vapor lamps and fluorescent lamps take advantage of the light given off when positive ions recombine with ...magnesium
(Encyclopedia)magnesium măgnēˈzēəm, –zhəm [key], metallic chemical element; symbol Mg; at. no. 12; at. wt. 24.3050; m.p. about 648.8℃; b.p. about 1,090℃; sp. gr. 1.738 at 20℃; valence +2. In 1808, Sir...fuel
(Encyclopedia)fuel, material that can be burned or otherwise consumed to produce heat. The common fuels used in industry, transportation, and the home are burned in air. The carbon and hydrogen in fuel rapidly comb...submarine
(Encyclopedia)submarine, naval craft capable of operating for an extended period of time underwater. Submarines are almost always warships, although a few are used for scientific, business, or other purposes (see a...environmentalism
(Encyclopedia)environmentalism, movement to protect the quality and continuity of life through conservation of natural resources, prevention of pollution, and control of land use. The philosophical foundations for ...Browse by Subject
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