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Lorentz contraction

(Encyclopedia)Lorentz contraction lôrˈĕnts [key], in physics, contraction or foreshortening of a moving body in the direction of its motion, proposed by H. A. Lorentz on theoretical grounds and based on an earli...

momentum

(Encyclopedia)momentum mōmĕnˈtəm [key], in mechanics, the quantity of motion of a body, specifically the product of the mass of the body and its velocity. Momentum is a vector quantity; i.e., it has both a magn...

Murchison, Sir Roderick Impey

(Encyclopedia)Murchison, Sir Roderick Impey mûrˈkĭsən [key], 1792–1871, British geologist. He served in the Napoleonic Wars but after the peace turned his attention to science. In the 1830s he undertook the i...

barcode

(Encyclopedia)CE5 Barcode barcode, computer coding system that uses a printed pattern of lines and bars to identify such things as products, mail and packages, and customer accounts; the term also is used for s...

activation energy

(Encyclopedia)CE5 Energy profile of an exothermic reaction: Although the total energy of the products is less than that of the reactants, the activation energy must be added to weaken or break existing bonds bef...

ventilation

(Encyclopedia)ventilation, process of supplying fresh air to an enclosed space and removing from it air contaminated by odors, gases, or smoke. Proper ventilation requires also that there be a movement or circulati...

Populist party

(Encyclopedia)Populist party, in U.S. history, political party formed primarily to express the agrarian protest of the late 19th cent. In some states the party was known as the People's party. In 1896, while th...

Homeland Security, United States Department of

(Encyclopedia)Homeland Security, United States Department of (DHS), executive department of the federal government charged with protecting the security of the American homeland as its main responsibility. Its prima...

International Bank for Reconstruction and Development

(Encyclopedia)International Bank for Reconstruction and Development (IBRD) (IBRD), independent specialized agency of the United Nations, with headquarters at Washington, D.C.; one of five closely associated develop...

Castlereagh, Robert Stewart, 2d Viscount

(Encyclopedia)Castlereagh, Robert Stewart, 2d Viscount kăˈsəlrā [key], 1769–1822, British statesman, b. Ireland. Entering the Irish Parliament in 1790 and the British Parliament in 1794, he was acting chief s...