RAJASTHAN PMT Rajasthan - PMT Solved Paper-2010

  • question_answer
    If pressure at half the depth of a lake is equal to 2/3 pressure at the bottom of the lake then what is the depth of the lake?

    A)  10 m                                    

    B)  20 m

    C)  60 m                    

    D)         30 m

    Correct Answer: B

    Solution :

    Pressure at bottom of the lake\[={{p}_{0}}+h\rho g\] Pressure at half the depth of a lake                 \[={{p}_{0}}+\frac{h}{2}\rho g\] According to given condition                 \[{{p}_{0}}+\frac{1}{2}h\rho g=\frac{2}{3}({{p}_{0}}+h\rho g)\] \[\Rightarrow \]               \[\frac{1}{3}{{p}_{0}}=\frac{1}{6}h\rho g\] \[\Rightarrow \]               \[h=\frac{2{{p}_{0}}}{\rho g}=\frac{2\times {{10}^{5}}}{{{10}^{3}}\times 10}=20\,\,m\]


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