Pressure: Difference between revisions
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Carl McBride (talk | contribs) (New page: The '''pressure''' is given by :<math>p = - \left.\frac{\partial A}{\partial V} \right\vert_{T,N} = kT \left.\frac{\partial \ln Q}{\partial V} \right\vert_{T,N}</math> where <math>A</mat...) |
Carl McBride (talk | contribs) m (Slight tidy.) |
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'''Pressure''' (<math>p</math>) is the force per unit area applied on a surface, in a direction perpendicular to that surface, i.e. the scalar part of the [[stress]] tensor. The SI units for pressure are Pascals (Pa). | |||
In thermodynamics the pressure is given by | |||
:<math>p = - \left.\frac{\partial A}{\partial V} \right\vert_{T,N} = | :<math>p = - \left.\frac{\partial A}{\partial V} \right\vert_{T,N} = k_BT \left.\frac{\partial \ln Q}{\partial V} \right\vert_{T,N}</math> | ||
where <math>A</math> is the [[Helmholtz energy function]], <math>V</math> is the volume and <math>Q (N,V,T)</math> | where <math>A</math> is the [[Helmholtz energy function]], <math>V</math> is the volume, <math>k_B</math> is the | ||
[[Boltzmann constant]], <math>T</math> is the [[temperature]] and <math>Q (N,V,T)</math> | |||
is the [[Canonical ensemble | canonical ensemble partition function]]. | is the [[Canonical ensemble | canonical ensemble partition function]]. | ||
==See also== | ==See also== | ||
Revision as of 12:16, 31 January 2008
Pressure () is the force per unit area applied on a surface, in a direction perpendicular to that surface, i.e. the scalar part of the stress tensor. The SI units for pressure are Pascals (Pa). In thermodynamics the pressure is given by
where is the Helmholtz energy function, is the volume, is the Boltzmann constant, is the temperature and is the canonical ensemble partition function.