Thermodynamics Question 37
Question: $ \Delta U+\Delta W=0 $ is valid for
[RPMT 2000]
Options:
A) 420K
B) $ 327^{o}C $
C) $ 300K $
D) $ -142^{o}C $
Show Answer
Answer:
Correct Answer: D
Solution:
$ {{T}^{\gamma }}{{P}^{1-\gamma }}= $ constant
Therefore $ T\propto {{P}^{\frac{\gamma -1}{\gamma }}} $
Therefore $ \frac{T _{2}}{T _{1}}={{( \frac{P _{2}}{P _{1}} )}^{\frac{\gamma -1}{\gamma }}}={{( \frac{1}{8} )}^{\frac{5/3-1}{5/3}}} $
$ T _{2}=300\times {{( \frac{1}{8} )}^{0.4}}=131K=-142{}^\circ C $
