EAMCET Medical EAMCET Medical Solved Paper-2007

  • question_answer
    A liquid drop of radius R breaks into 64 tiny drops each of radius r. If the surface tension of the liquid is T, then the gain in energy is

    A)  \[48\,\pi {{R}^{2}}T\]                                    

    B)  \[12\,\pi {{r}^{2}}T\]

    C)  \[96\pi {{R}^{2}}T\]                                       

    D)  \[192\pi {{r}^{2}}T\]

    Correct Answer: D

    Solution :

                     Volume of big drop = 64 \[\times \]volume of tiny  drops or            \[\frac{4}{3}\pi {{R}^{3}}=64\times \frac{4}{3}\pi {{r}^{3}}\] or            \[R=4r\] So, the gain in surface energy = work done in splitting a liquid drop of radius R into n identical drops \[=4\pi T{{R}^{2}}({{n}^{1/3}}-1)\] \[=4\pi T\,{{(4r)}^{2}}({{64}^{1/3}}-1)=192\pi {{r}^{2}}T\]


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