Definition:SI/Energy/Joule

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Definition

The joule is the SI unit of energy.


It is defined as being:

the energy transferred to (or work done on) a body when a force of $1$ newton acts on that body in the direction of the force's motion through a distance of $1$ metre
the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second.

Thus:

$1 \, \mathrm J = 1 \, \mathrm N \, \mathrm m$


Conversion Factors

\(\ds \) \(\) \(\ds 1\) joule
\(\ds \) \(=\) \(\ds 10^7\) ergs
\(\ds \) \(=\) \(\ds 0.7376\) foot-pound
\(\ds \) \(=\) \(\ds 0.2389\) $15 \cels$ calorie
\(\ds \) \(=\) \(\ds 9.481 \times 10^{-4}\) British thermal unit


Symbol

$\mathrm J$

The symbol for the joule is $\mathrm J$.


Its $\LaTeX$ code is \mathrm J .


Base Units

The SI base units of the joule are:

$\mathrm J := \mathrm {kg} \, \mathrm m^2 \mathrm s^{-2}$

where:

$\mathrm {kg}$ denotes kilograms
$\mathrm m$ denotes metres
$\mathrm s$ denotes seconds (of time).


Source of Name

This entry was named for James Prescott Joule.


Sources

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