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harmonic motion

(Encyclopedia)CE5 Harmonic motion is exhibited by a weight vibrating on the end of a spring. In A, the displacement of the object from its equilibrium position and the acceleration of the object are at a maximum...

Great Awakening

(Encyclopedia)Great Awakening, series of religious revivals that swept over the American colonies about the middle of the 18th cent. It resulted in doctrinal changes and influenced social and political thought. In ...

pilaster

(Encyclopedia)pilaster pĭlăsˈtər [key], in architecture, upright supporting member, attached to and projecting slightly from the face of a wall and equipped with a base and capital like a column; also, a simila...

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...

San Diego

(Encyclopedia)San Diego săn dēāˈgō [key], city (1990 pop. 1,110,549), seat of San Diego co., S Calif., on San Diego Bay; inc. 1850. San Diego includes the unincorporated communities of La Jolla and Spring Vall...

aviation medicine

(Encyclopedia)aviation medicine, scientific study of the biological effects of aviation, especially on human beings. Although aviation medicine is concerned with such problems as the spread of diseases by persons t...

inclined plane

(Encyclopedia)CE5 Inclined plane inclined plane, simple machine, consisting of a sloping surface, whose purpose is to reduce the force that must be applied to raise a load. To raise a body vertically a force mu...

equal-time rule

(Encyclopedia)equal-time rule, a Federal Communications Commission rule that requires equal air time for all major candidates competing for political office. It was preceded by the fairness doctrine, abolished in 1...

Guericke, Otto von

(Encyclopedia)Guericke, Otto von ôˈtō fən gāˈrĭkə [key], 1602–86, German physicist, noted for his study of pneumatics. He carried out his most important researches while burgomaster (1646–81) of Magdebu...

thunder

(Encyclopedia)thunder, sound produced along a path of a lightning flash, caused by the rapid heating and expansion of the adjacent air; lightning can heat air to temperatures as much as five times hotter than those...