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AFMC AFMC Solved Paper-2008

  • question_answer
    An air bubble of radius 1 cm rises from the bottom portion through a liquid of density 1.5 g/cc at a constant speed of 0.25 cm s-1. If the density of air is neglected, the coefficient of viscosity of the liquid is approximately, (In Pa)

    A) 13000                                   

    B) 1300

    C) 130                                        

    D) 13

    Correct Answer: C

    Solution :

    \[v=\frac{2}{9}\frac{{{r}^{2}}\rho g}{\eta }\] \[\Rightarrow \]  \[\eta =\frac{2}{9}.\frac{{{r}^{2}}\rho g}{v}\] \[=\frac{2}{9}\frac{(1\times {{10}^{-2}})\times (1.5\times {{10}^{3}})\times 9.8}{0.25\times {{10}^{-2}}}\]\[=130Pa-s\]


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