# joule

(redirected from*Petajoule*)

Also found in: Dictionary, Thesaurus, Medical.

## joule

(jo͞ol, joul), abbr. J, unit of work**work,**

in physics and mechanics, transfer of energy by a force acting to displace a body. Work is equal to the product of the force and the distance through which it produces movement.

**.....**Click the link for more information. or energy

**energy,**

in physics, the ability or capacity to do work or to produce change. Forms of energy include heat, light, sound, electricity, and chemical energy. Energy and work are measured in the same units—foot-pounds, joules, ergs, or some other, depending on the system of

**.....**Click the link for more information. in the mks system

**mks system,**

system of units of measurement based on the metric system and having the meter of length, the kilogram of mass, and the second of time as its fundamental units. Other mks units include the newton of force, the joule of work or energy, and the watt of power.

**.....**Click the link for more information. of units, which is based on the metric system

**metric system,**

system of weights and measures planned in France and adopted there in 1799; it has since been adopted by most of the technologically developed countries of the world.

**.....**Click the link for more information. ; it is the work done or energy expended by a force of 1 newton acting through a distance of 1 meter. The joule is named for James P. Joule.

## joule

(jool) Symbol: J. The SI unit of energy, equal to the work done when the point of application of a force of one newton is moved one meter in the direction of the force.## Joule

a unit of energy and work in the International System of Units and the MKSA (meter-kilogram-second-ampere) system. It is equal to the work done by a force of 1 newton in moving a body 1 m in the direction of the force. It is named in honor of the English physicist J. Joule. In Russian the symbol is *dzh;* the international symbol is J.

At the Second World Conference of Electrical Engineers (1889) the joule was introduced into the absolute practical electrical units as the unit of work and energy for electric current. The joule was defined as the work done at a power of 1 watt in 1 second. The International Conference on Electrical Units and Standards (London, 1908) established “international” electrical units, among them the so-called international joule. After the return to absolute electrical units (beginning Jan. 1, 1948), the ratio of 1 international joule to 1.00020 absolute joules was adopted.

The joule is also used as a unit of quantity of heat. The ratio of the joule to other units is as follows: 1 joule = 10^{7} ergs = 0.2388 calories.

G. D. BURDUN

## joule

[jül*or*jau̇l]

## joule

## joule

^{7}ergs, 0.2390 calories, or 0.738 foot-pound

## Joule

**James Prescott.**1818--89, English physicist, who evaluated the mechanical equivalent of heat and contributed to the study of heat and electricity