JEE Main & Advanced Sample Paper JEE Main Sample Paper-32

  • question_answer
    A bubble rises from bed of a lake to its surface. The depth of lake is 103 times the value by which bubble increases in size. If the atmospheric pressure is equal to pressure due to a column of water of 10 m, find the value by which bubble increases in size (approximately)

    A) 100         

    B)                                    10

    C) \[10\sqrt{2}\]    

    D)                                    \[10\sqrt{3}\]

    Correct Answer: B

    Solution :

    \[{{P}_{1}}{{V}_{1}}={{P}_{2}}{{V}_{2}}\]                 \[{{P}_{1}}.\frac{4}{3}\pi {{r}^{3}}=10.\left[ \frac{4}{3}\pi {{(kr)}^{3}} \right]\]                 \[{{P}_{1}}=10{{K}^{3}}={{P}_{2}}\]+ depth of lake                 \[=10+{{10}^{3}}K.\] \[10{{K}^{3}}-{{10}^{3}}K-10=0\] \[{{K}^{3}}-{{10}^{2}}K-1=0\] Or \[\left( \frac{-a}{2} \right)\,\times \frac{1}{3}=1\,\Rightarrow a=6\]


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