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second

(Encyclopedia)second, abbr. sec or s, fundamental unit of time in all systems of measurement. In practical terms, the second is 1/60 of a minute, 1/3,600 of an hour, or 1/86,400 of a day. Since the length of the da...

absolute zero

(Encyclopedia)absolute zero, the zero point of the ideal gas temperature scale, denoted by 0 degrees on the Kelvin and Rankine temperature scales, which is equivalent to −273.15℃ and −459.67℉. For most gase...

Afars and the Issas, French Territory of the

(Encyclopedia)Afars and the Issas, French Territory of the: see Djibouti, republic. ...

Burbank

(Encyclopedia)Burbank, city (2020 pop.107,337), Los Angeles co., S Calif.; inc. 1911. Tourism and the entertainment industry are central to its economy; several motio...

dimension, in physics

(Encyclopedia)dimension, in physics, an expression of the character of a derived quantity in relation to fundamental quantities, without regard for its numerical value. In any system of measurement, such as the met...

Doppler effect

(Encyclopedia)Doppler effect, change in the wavelength (or frequency) of energy in the form of waves, e.g., sound or light, as a result of motion of either the source or the receiver of the waves; the effect is nam...

Americas, antiquity and prehistory of the

(Encyclopedia)Americas, antiquity and prehistory of the, study of the origins of the aboriginal peoples of the Americas. Archaeologists believe humans had entered and occupied much of the Americas by the end of the...

precession of the equinoxes

(Encyclopedia)CE5 Precession of the equinoxes (the points at which the earth's celestial equator intersects its ecliptic) is due to the slow rotation of the earth's axis around a perpendicular to the ecliptic. ...

motor, electric

(Encyclopedia)CE5 Motor: In the AC motor, current fed to the conducting loop of wire causes it to rotate in the magnetic field, thus turning the shaft on which the loop is mounted. In the DC motor, the direction...

Democritus

(Encyclopedia)Democritus dĭmŏkˈrĭtəs [key], c.460–c.370 b.c., Greek philosopher of Abdera; pupil of Leucippus. His theory of the nature of the physical world was the most radical and scientific attempted up ...