CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2007

  • question_answer
    A tank of height H is fully filled with water. If the water rushing from a hole made in the tank below the free surface, strikes the floor at maximum horizontal distance, then the depth of the hole from the free surface must be

    A)  \[\left( \frac{3}{4} \right)H\]     

    B)         \[\left( \frac{2}{3} \right)H\]     

    C)         \[\left( \frac{1}{4} \right)H\]     

    D)         \[\left( \frac{1}{2} \right)H\]

    E)  \[\left( \frac{1}{3} \right)H\]

    Correct Answer: D

    Solution :

    As hole is made in the tank below the free surface of water, so water rushing from this hole follows a parabolic path. The velocity of efflux of liquid,                 \[v=\sqrt{2gh}\] Time      \[t=\sqrt{\frac{2(H-h)}{g}}\] Horizontal range, \[R=vt\]                 \[R={{\left( 2gh\times \frac{2(H-h)}{g} \right)}^{1/2}}\] ie,           \[{{R}^{2}}=4h(H-h)=4(Hh-{{h}^{2}})\] The range is maximum if                 \[\frac{dR}{dh}=0\] or            \[\frac{2RdR}{dh}=4(H-2h)\] or            \[0=(H-2h)\] or            \[h=\frac{H}{2}\]


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