Physics · Ch 8 — Heat and Thermodynamics
PV Diagram
PV Diagram
A P-V diagram (Figure 8.22) plots a system's pressure against its volume as it undergoes a process, and is the standard graphical tool of thermodynamics because the area under the traced curve, between the initial and final volumes, directly equals the work done by (or on) the gas during that process -- exactly the geometric meaning of the integral developed in the previous section. The shape of the curve traced on a - diagram depends entirely on which type of thermodynamic process is occurring: a horizontal line for an isobaric (constant-pressure) process, a vertical line for an isochoric (constant-volume) process, a hyperbola for an isothermal (constant-temperature) process, and a steeper hyperbola-like curv …
What this figure shows. A generic curve on a P-V diagram running from an initial point (Pi, Vi) to a final point (Pf, Vf), with the region between the curve and the V-axis, from Vi to Vf, shaded to represent the work done. A caption states the work equals the integral of P dV between the two limits. This is the general template figure the textbook later specialises into the isotherm, adiabat, isobar and isochore shapes for each named proc …