A vessel contains 0.15 m 3 of a gas at pressure 8 bar and temperature 140 ° C with c p = 3 R and c v = 2 R . It is expanded adiabatically till pressure falls to 1 bar. The work done during this process is kJ. (R is gas constant)

Physics · Thermodynamics

JEE Main 2026 — 2 April, Morning Shift — Question 16

A vessel contains $0.15\mathrm{m}^3$ of a gas at pressure 8 bar and temperature $140^{\circ}\mathrm{C}$ with $\mathrm{c}_{\mathrm{p}} = 3\mathrm{R}$ and $\mathrm{c}_{\mathrm{v}} = 2\mathrm{R}$ . It is expanded adiabatically till pressure falls to 1 bar. The work done during this process is ______ kJ. (R is gas constant)

Answer: 120

Numerical answer — enter this value.

Step-by-step solution

$\gamma = 1.5$ , $V_2 = (P_1/P_2)^{1/\gamma} V_1 = 8^{2/3}\times0.15 = 0.6 m^3$ , $W = \frac{P_1V_1-P_2V_2}{\gamma-1} = 1.2\times10^5 J = 120 kJ$

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Exam: JEE Main 2026
Paper: 2 April, Morning Shift
Subject: Physics
Chapter: Thermodynamics
Topic: Different Thermodynamic Processes

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Answer: 120

Step-by-step solution

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