Work: Difference between revisions
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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, where the system evolves through a succession of equilibrium states, one has | ||
:<math>\left.dW\right.=-p~dV </math> | :<math>\left.dW\right.=-p~dV </math> | ||
Latest revision as of 10:22, 5 July 2011
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, where the system evolves through a succession of equilibrium states, one has
and for irreversible changes
