periodic disturbing force
11mathematics — /math euh mat iks/, n. 1. (used with a sing. v.) the systematic treatment of magnitude, relationships between figures and forms, and relations between quantities expressed symbolically. 2. (used with a sing. or pl. v.) mathematical procedures,… …
12Germany — /jerr meuh nee/, n. a republic in central Europe: after World War II divided into four zones, British, French, U.S., and Soviet, and in 1949 into East Germany and West Germany; East and West Germany were reunited in 1990. 84,068,216; 137,852 sq.… …
13electromagnetic radiation — Physics. radiation consisting of electromagnetic waves, including radio waves, infrared, visible light, ultraviolet, x rays, and gamma rays. [1950 55] * * * Energy propagated through free space or through a material medium in the form of… …
14Spain — /spayn/, n. a kingdom in SW Europe. Including the Balearic and Canary islands, 39,244,195; 194,988 sq. mi. (505,019 sq. km). Cap.: Madrid. Spanish, España. * * * Spain Introduction Spain Background: Spain s powerful world empire of the 16th and… …
15Inner German border — Innerdeutsche Grenze North and central Germany …
16science, history of — Introduction the history of science from its beginnings in prehistoric times to the 20th century. On the simplest level, science is knowledge of the world of nature. There are many regularities in nature that mankind has had to… …
17Judaism — /jooh dee iz euhm, day , deuh /, n. 1. the monotheistic religion of the Jews, having its ethical, ceremonial, and legal foundation in the precepts of the Old Testament and in the teachings and commentaries of the rabbis as found chiefly in the… …
18Albert Einstein — Einstein redirects here. For other uses, see Einstein (disambiguation) …
19musical sound — Introduction any tone with characteristics such as controlled pitch and timbre. The sounds are produced by instruments in which the periodic vibrations can be controlled by the performer. That some sounds are intrinsically musical,… …
20Russia — /rush euh/, n. 1. Also called Russian Empire. Russian, Rossiya. a former empire in E Europe and N and W Asia: overthrown by the Russian Revolution 1917. Cap.: St. Petersburg (1703 1917). 2. See Union of Soviet Socialist Republics. 3. See Russian… …
