# Difference between revisions of "Work"

Carl McBride (talk | contribs) |
(W=-pdV on compression or expansion, but always ''upon'' (I am 98% sure)) |
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− | The mechanical '''work''', ''W'', performed | + | The mechanical '''work''', ''W'', performed ''upon'' a gas is given by |

:<math>W = - \int_\alpha^\beta p ~dV</math> | :<math>W = - \int_\alpha^\beta p ~dV</math> | ||

where <math>\alpha</math> and <math>\beta</math> are points in state space, ''p'' is the [[pressure]] | where <math>\alpha</math> and <math>\beta</math> are points in state space, ''p'' is the [[pressure]] | ||

− | and ''V'' is the volume. | + | and ''V'' is the volume. The mechanical work done ''by'' the gas has the opposite sign (a common |

+ | source of mistakes). | ||

− | For reversible changes | + | For reversible changes, |

:<math>\left.dW\right.=-p~dV </math> | :<math>\left.dW\right.=-p~dV </math> |

## Revision as of 10:07, 8 June 2009

The mechanical **work**, *W*, performed *upon* a gas is given by

where and are points in state space, *p* is the pressure
and *V* is the volume. The mechanical work done *by* the gas has the opposite sign (a common
source of mistakes).

For reversible changes,

and for irreversible changes