Mathematics and Physics Glossary

Join, n. (Geom.) The line joining two points; the point common to two intersecting lines. Henrici.

Joint, a. (Math.) Involving two or more variables.

Jordan curve, n. (Math.) [After French mathematician Camille Jordan, 1838-1922] See Simple closed curve.

Jordan curve theorem, n. (Math.) The theorem that states that every simple closed curve divides a plane into two parts and acts as the common boundary between them.

Joule, n. [From English physicist, James P. Joule.] (Phys.) A unit of work which is equal to 10⁷ units of work in the C. G. S. system of units (ergs), and is practically equivalent to the energy expended in one second by an electric current of one ampere in a resistance of one ohm. One joule is approximately equal to 0.738 foot pounds.

Joule's cycle. (Phys.) The cycle for the air engine proposed by Joule. In it air is taken by a pump from a cold chamber and compressed adiabatically until its pressure is eqal to that of the air in a hot chamber, into which it is then delivered, thereby displacing an equal amount of hot air into the engine cylinder. Here it expands adiabatically to the temperature of the cold chamber into which it is finally exhausted. This cycle, reversed, is used in refrigerating machines.