Columbia Encyclopedia

Search results

500 results found

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...

Strauss, Lewis Lichtenstein

(Encyclopedia)Strauss, Lewis Lichtenstein strôz [key], 1896–1974, American financier, chairman of the Atomic Energy Commission (1953–58), b. Charleston, W.Va. In World War I he served under Herbert Hoover on t...

spring, in mechanics

(Encyclopedia)spring, in mechanics, any of several elastic devices used variously to store and to furnish energy, to absorb shock, to sustain the pressure between contacting surfaces, and to resist tensional or com...

fuel cell

(Encyclopedia)fuel cell, electric cell in which the chemical energy from the oxidation of a gas fuel is converted directly to electrical energy in a continuous process (see oxidation and reduction). The efficiency ...

photochemistry

(Encyclopedia)photochemistry, study of chemical processes that are accompanied by or catalyzed by the emission or absorption of visible light or ultraviolet radiation. A molecule in its ground (unexcited) state can...

superfluidity

(Encyclopedia)superfluidity, tendency of liquid helium below a temperature of 2.19K to flow freely, even upward, with little apparent friction. Helium becomes a liquid when it is cooled to 4.2K. Special methods...

machine

(Encyclopedia)machine, arrangement of moving and stationary mechanical parts used to perform some useful work or to provide transportation. From a historical perspective, many of the first machines were the result ...

North Dakota, University of

(Encyclopedia)North Dakota, University of, at Grand Forks; state supported; coeducational; chartered 1883, opened 1884. It has several professional schools, including those for aerospace sciences, engineering and m...

glycolysis

(Encyclopedia)glycolysis glīkŏlˈĭsĭs [key], term given to the metabolic pathway utilized by most microorganisms (yeast and bacteria) and by all “higher” animals (including humans) for the degradation of gl...

dating

(Encyclopedia)dating, the determination of the age of an object, of a natural phenomenon, or of a series of events. There are two basic types of dating methods, relative and absolute. In relative dating, the tempor...