JCECE Engineering JCECE Engineering Solved Paper-2009

  • question_answer
    A rectangular vessel when full of water, takes \[10\,\,\min \] to be emptied through an orifice in its bottom. How much time will it take to be emptied when half filled with water?

    A) \[9\,\,\min \]                    

    B) \[7\,\,\min \]

    C) \[5\,\,\min \]                    

    D) \[3\,\,\min \]

    Correct Answer: B

    Solution :

    If \[{{A}_{0}}\] is the area of orifice at the bottom below free surface and \[A\] that of vessel, time \[t\] taken be empited the tank,                 \[t=\frac{A}{{{A}_{0}}}\sqrt{\frac{2H}{g}}\] \[\therefore \]  \[\frac{{{t}_{1}}}{{{t}_{2}}}=\sqrt{\frac{{{H}_{1}}}{{{H}_{2}}}}\] \[\Rightarrow \]               \[\frac{t}{{{t}_{2}}}=\sqrt{\frac{{{H}_{2}}}{{{H}_{1}}/2}}\] \[\Rightarrow \]               \[\frac{t}{{{t}_{2}}}=\sqrt{2}\] \[\therefore \]  \[{{t}_{2}}=\frac{t}{\sqrt{2}}=\frac{10}{\sqrt{2}}=5\sqrt{2}\]


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