JEE Main & Advanced Sample Paper JEE Main Sample Paper-35

  • question_answer
    Two cylinders fitted with pistons and placed as shown, connected with string through a small tube of negligible volume, are filled with a gas at pressure \[{{P}_{0}}\] and temperature \[{{T}_{0}}\]. The radius of smaller cylinder is half of the other. If the temperature is increased to \[2{{T}_{0}}\], find the pressure, if the piston of bigger cylinder moves towards left by 1 metre?                          

    A)  \[\frac{4}{5}{{P}_{0}}\]                                

    B)  \[\frac{3}{5}{{P}_{0}}\]

    C)  \[\frac{2}{5}{{P}_{0}}\]                                                

    D)  \[\frac{5}{4}{{P}_{0}}\]

    Correct Answer: D

    Solution :

    Initial volume \[=1\,\times \left[ \pi {{R}^{2}}\,+\frac{\pi {{R}^{2}}}{4} \right]=\frac{5}{4}\pi {{R}^{2}}\]             Piston moves towards left by one metre on heating. Additional volume available due to heating             \[=1\times \pi {{R}^{2}}-\frac{1+\pi {{R}^{2}}}{4}=\frac{3}{4}\,\pi {{R}^{2}}\] Total volume after heating \[=2\pi {{R}^{2}}\]             \[{{P}_{0}}\times \frac{5}{4}\,\pi {{R}^{2}}\,=nR{{T}_{0}}\]                                     ?(1) After heating, \[{{P}_{2}}\,\times 2\pi {{R}^{2}}\,=nR\,\times 2{{T}_{0}}\]      ...(2)             \[\frac{{{P}_{0}}}{{{P}_{2}}}\times \frac{5}{4}\times \frac{1}{2}\,=\frac{1}{2}\]           \[{{P}_{2}}=\frac{5}{4}\,{{P}_{0}}\]


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