BCECE Medical BCECE Medical Solved Papers-2005

  • question_answer
    Water is flowing in a pipe of diameter 4 cm with a velocity 3 m/s. The water then enters into a pipe of diameter 2 cm. The velocity of water in the other pipe is :

    A)  3 m/s         

    B)  6 m/s

    C)  12 m/s        

    D)  8 m/s

    Correct Answer: C

    Solution :

    According to principle of continuity, when an incompressible and non-viscous liquid flows in a streamlined motion through a tube of non-uniform cross-section, then the product of the area of cross-section and the velocity of flow is same at every point in the tube. Thus,     Av = constant or            \[{{A}_{1}}{{v}_{1}}={{A}_{2}}{{v}_{2}}\] or            \[\pi {{r}_{1}}^{2}{{v}_{1}}=\pi {{r}_{2}}^{2}{{v}_{2}}\] Given,   \[{{r}_{1}}=\frac{4}{2}cm=0.02\,m\],                 \[{{r}_{2}}=\frac{2}{2}\,cm=0.02\,m\],                 \[{{v}_{1}}=3\,m/s\] \[\therefore \] \[\pi {{(0.02)}^{2}}\times 3=\pi {{(0.01)}^{2}}{{v}_{2}}\] or \[{{v}_{2}}={{\left( \frac{0.02}{0.01} \right)}^{2}}\times 3\]


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