JEE Main & Advanced Physics Fluid Mechanics, Surface Tension & Viscosity / द्रव यांत्रिकी, भूतल तनाव और चिपचिपापन Question Bank Fluid Flow

  • question_answer
    Two water pipes of diameters 2 cm and 4 cm are connected with the main supply line. The velocity of flow of water in the pipe of 2 cm diameter is                                      [MNR 1980]

    A)            4 times that in the other pipe

    B)            \[\frac{1}{4}\] times that in the other pipe

    C)            2 times that in the other pipe                                           

    D)            \[\frac{1}{2}\] times that in the other pipe

    Correct Answer: A

    Solution :

                       \[{{d}_{A}}=2\,cm\]and\[{{d}_{B}}=4\ cm\] \[\therefore \ \ {{r}_{A}}=1\ cm\] and \[{{r}_{B}}=2\ cm\] From equation of continuity,  av = constant \ \[\frac{{{v}_{A}}}{{{v}_{B}}}=\frac{{{a}_{B}}}{{{a}_{A}}}=\frac{\pi {{({{r}_{B}})}^{2}}}{\pi {{({{r}_{A}})}^{2}}}={{\left( \frac{2}{1} \right)}^{2}}\Rightarrow {{v}_{A}}=4{{v}_{B}}\]


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