JEE Main & Advanced Physics Thermodynamical Processes Question Bank Self Evaluation Test - Thermodynamics

  • question_answer
    Figure shows the variation of internal energy (U) with the pressure (P) of 2.0 mole gas in cyclic process abcda. The temperature of gas at c and d are 300 K and 500 K. calculate the heat absorbed by the gas during the process.

    A) 400 R In 2        

    B)        200 R In 2

    C) 100 R In 2        

    D)        300 R In 2

    Correct Answer: A

    Solution :

    [a] Change in internal energy for cyclic process \[\left( \Delta U \right)=0.\] For process \[a\to b\], (P-constant) \[{{W}_{a\to b}}=P\Delta V\] \[=nR\Delta T=-400R\] For process \[b\to c\](T-constant) \[{{W}_{b\to c}}=-2R(300)\,\,\text{ln 2}\] For process \[c\to d\], (P-constant) \[{{W}_{c\to d}}=+\,400R\] For process \[d\to a\], (T-constant) \[{{W}_{d\to a}}=+2R(500)\text{ ln 2 }\] Net work (AW) \[={{W}_{a\to b}}+{{W}_{b\to c}}+{{W}_{c\to d}}+{{W}_{d\to a}}\] \[\Delta W=400R\text{ ln 2}\] \[\therefore dQ=dU+dW\], first law of thermodynamics \[\therefore dQ=400R\text{ ln }2.\]


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