View Single Post
Philip Wood
#2
Nov14-12, 10:02 AM
PF Gold
P: 963
Yes, but there are other cases where the 'dissipative' label might be misleading. An example would be a gas expanding into a small extra evacuated volume, ΔV. Since the extra volume is small the gas pressure, p, is hardly affected, so pΔV has a definite, non-zero value. Yet the expanding gas does no external work, as no force resists its expansion. [If the expansion is into a large extra evacuated volume, we can't even calculatepΔV, as the change is non-quasi-static and pressure does not change with volume in a defined way.]