J & K CET Medical J & K - CET Medical Solved Paper-2014

  • question_answer
    When the gas expands with temperature using the relation\[V=K{{T}^{2/3}}\]for the temperature change of 40 K, the work done is

    A)  \[20.1\,R\]       

    B)  \[30.2\,R\]

    C)  \[26.6\,R\]          

    D)  \[35.6\,R\]

    Correct Answer: C

    Solution :

     \[W=\int{pdV}\] \[=\int{\frac{\mu RT}{V}}dV\]             \[=\int{\frac{\mu RT}{K{{T}^{\frac{2}{3}}}}}dV\] ...(i) \[\because \] \[V=K{{T}^{\frac{2}{3}}}\] \[dV=K\frac{2}{3}{{T}^{-1/3}}dT\]            ...(ii) From Eqs. (i) and (ii) \[W=\int{\frac{\mu RT}{K{{T}^{\frac{2}{3}}}}\times k\frac{2}{3}{{T}^{-1/3}}}dT\] \[=\frac{2}{3}R\int{{{T}^{-1-\frac{1}{3}-\frac{2}{3}}}}dT\] \[=\frac{2}{3}R\int_{0}^{40}{{{T}^{0}}d}T=\frac{2}{3}R(T)_{0}^{40}\] \[=\frac{2}{3}R(40-0)=\frac{80R}{3}=26.6\,R\]


You need to login to perform this action.
You will be redirected in 3 sec spinner