Project ForgeProcess Calculations
Laws of Thermodynamics
GATE 2014
Medium
In a closed system, the isentropic expansion of an ideal gas with constant specific heats is represented on a ln(P) vs ln(V) plot by a line that is
- Aincreasing, on a P vs V plot
- Bdecreasing, on a P vs V plot
- Cincreasing, on a ln(P) vs ln(V) plot
- decreasing, on a ln(P) vs ln(V) plot
Explanation
Isentropic expansion of an ideal gas follows PV^γ=const, i.e. ln(P)=const−γ·ln(V) — a straight line of NEGATIVE slope (−γ) on a ln(P) vs ln(V) plot. On a plain P vs V plot the relation is a curve, not a straight line, so only the ln-ln decreasing-line description is correct.
Source: GATE CH 2014 (2014)
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