Thermodynamics, Statistical Physics, and Quantum Mechanics

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4.32 Joule Cycle (Stony Brook)

The efficiency of the cycle is given by the work W during the cycle divided
by the heat absorbed in path (see FigureS.4.32). Wis defined
by the area enclosed by the four paths of the P–V plot. The integral
PdValong the paths ofconstant pressure and issimply the

adiabats, where there is noheattransfer isgiven by the change in
internal energy

Substituting theideal gas law into (S.4.32.1) and rearranging,
wefind

What remains is towriteWand in terms ofPand form thequotient.
Using the equation for an adiabaticprocess in an alternativeform,

where weused In the process the gas absorbs the
heat

THERMODYNAMICS AND STATISTICAL PHYSICS

difference in volume of the ends times the pressure, and the work along the