JEE Mains · Physics · STD 11 - Thermodynamics
- JEE Mains 2024
- Hard
- MCQ
A real gas within a closed chamber at \(27^{\circ} \mathrm{C}\) undergoes the cyclic process as shown in figure. The gas obeys \(P V^3=\mathrm{RT}\) equation for the path \(A\) to \(B\). The net work done in the complete cycle is _______.(assuming \(R=8 \mathrm{~J} / \mathrm{molK}\) )
Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(205 \mathrm{~J}\)
Step-by-step Solution
Detailed explanation
\(\mathrm{W}_{\mathrm{AB}} =\int \mathrm{PdV} \quad \text { (Assuming } \mathrm{T} \text { to be constant) }\)
\(=\int \frac{\mathrm{RTdV}}{\mathrm{V}^3}\)
\(=\mathrm{RT} \int_2^4 \mathrm{~V}^{-3} \mathrm{dV}\)
\(=8 \times 300 \times\left(-\frac{1}{2}\left[\frac{1}{4^2}-\frac{1}{2^2}\right]\right)\)
\(=225 \mathrm{~J}\)
\(\mathrm{~W}_{\mathrm{BC}} =\mathrm{P} \int_4^2 \mathrm{dV}=10(2-4)=-20 \mathrm{~J}\)
\(\mathrm{~W}_{\mathrm{CA}} =0\)
\(\therefore \mathrm{W}_{\text {cyck }} =205 \mathrm{~J}\)
Note: Data is inconsistent in process \(A B\).
So needs to be challenged.
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