JEE Main & Advanced Sample Paper JEE Main - Mock Test - 18

  • question_answer
    A gas expands with temperature according to the relation \[V=K{{T}^{2/3}}\]. Calculate work done when the temperature changes by 60 K?

    A) 10 R     

    B) 30 R 

    C) 40 R     

    D) 20 R

    Correct Answer: C

    Solution :

    [c]: \[dW=PdV=\frac{RT}{V}dV\]                                   ...(i) As \[V=K{{T}^{2/3}}\therefore dV=K\frac{2}{3}{{T}^{-1/3}}dT\] \[\therefore \]\[\frac{dV}{V}=\frac{K\frac{2}{3}{{T}^{-1/3}}dT}{K{{T}^{2/3}}}=\frac{2}{3}\frac{dT}{T}\] From (i),\[W=\int\limits_{{{T}_{1}}}^{{{T}_{2}}}{RT}\frac{dV}{V}=\int\limits_{{{T}_{1}}}^{{{T}_{2}}}{RT}\frac{2}{3}\frac{dT}{T}\] \[W=\frac{2}{3}R({{T}_{2}}-{{T}_{1}})=\frac{2}{3}R\times 60=40R\]


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