BHU PMT BHU PMT Solved Paper-2001

  • question_answer
    An ideal gas at \[27{}^\circ C\] is compressed Adiabatically to \[\frac{8}{27}\] of its original volume if \[\gamma =\frac{5}{3}\], Then rise in temperature is:

    A)  \[405\,\,K\]                      

    B)  \[225\,\,K\]

    C)  \[375\,\,K\]      

    D)  \[450\,\,K\]

    Correct Answer: C

    Solution :

    When a system undergoes a change under the condition that no exchange of heat takes place between systems and surrounding then, such a process is called an adiabatic one. The relation between temperature\[\left( T \right)\], volume \[\left( V \right)\] and ratio of specific heats \[\left( \gamma  \right)\] is \[T{{V}^{\gamma -1}}=\]Constant \[\therefore \]  \[\frac{T'}{T}={{\left( \frac{V}{V'} \right)}^{\gamma -1}}={{\left( \frac{27}{8} \right)}^{\frac{5}{3}-1}}={{\left( \frac{27}{8} \right)}^{\frac{2}{3}}}\] \[\Rightarrow \]               \[\frac{T'}{T}={{\left( \frac{27}{8} \right)}^{2/3}}={{\left( \frac{3}{2} \right)}^{2}}=\frac{9}{4}\] \[\Rightarrow \]               \[T'=T\times \frac{9}{4}=\left( 273+27 \right)\times \frac{9}{4}\]      \[=300\times \frac{9}{4}=675\,K\] \[\therefore \,\Delta T=T'-T=\left( 675-300 \right)K=375\,K\]     


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