Pressure Definition aF = oNe( n Working expression 6wPressure ( ) 3 1 1 r r N N i i i U N P     = = −     '( ) ( , ) 6 1 1 2 (2) r 1 r 2r1 2 r1 2 r r d d u N         = − ( )          =−  = V Z TV N V F T N T N P k T ln ( , , ) , , Definition: Working expression: