AMU Medical AMU Solved Paper-2012

  • question_answer
    The terminal speed attained by an aluminium sphere of radius 1 mm falling through water at \[{{20}^{o}}C\] will be close to

    A)  9.2 m/s               

    B)  6.9 m/s

    C)  4.6m/s                

    D)  2.3 m/s                

    Correct Answer: C

    Solution :

                    Specific gravity of Al = 2.7 Density of air \[=2.7\times {{10}^{3}}kg/{{m}^{3}}\] Terminal velocity                 \[v=\frac{2{{r}^{2}}(\rho -\sigma )g}{9\eta }\]             \[v=\frac{2\times {{(1\times {{10}^{-3}})}^{2}}(2.7\times {{10}^{3}}-1000)\times 9.8}{8\times 9\times {{10}^{4}}}\] Terminal velocity v = 4.5 m/s.                 (Assume laminar flow, specific gravity of \[Al=2.7\] and \[{{\eta }_{water}}=8\times {{10}^{-4}}pl\]


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