Thermodynamics Question 2
Question 2 - 2024 (01 Feb Shift 2)
A diatomic gas $(\gamma=1.4)$ does $200 \mathrm{~J}$ of work when it is expanded isobarically. The heat given to the gas in the process is:
(1) $850 \mathrm{~J}$
(2) $800 \mathrm{~J}$
(3) $600 \mathrm{~J}$
(4) $700 \mathrm{~J}$
Show Answer
Answer: (4)
Solution:
$\gamma=1+\frac{2}{\mathrm{f}}=1.4 \Rightarrow \frac{2}{\mathrm{f}}=0.4$
$\Rightarrow \mathrm{f}=5$
$\mathrm{W}=\mathrm{n} R \Delta \mathrm{T}=200 \mathrm{~J}$
$\mathrm{Q}=\left(\frac{\mathrm{f}+2}{2}\right) \mathrm{nR} \Delta \mathrm{T}$
$=\frac{7}{2} \times 200=700 \mathrm{~J}$
