JEE Main & Advanced Sample Paper JEE Main - Mock Test - 28

  • question_answer
    A large open tank has two holes in the wall. One is a square hole of side L at a depth y from the top and the other is a circular hole of radius R at a depth 4y from the top. When the tank is completely filled with water the quantities of water flowing out per second from both the holes are the same. Then R is equal to

    A) \[2\pi L\]

    B) \[\frac{L}{\sqrt{2\pi }}\]

    C) L                                 

    D) \[\frac{L}{2\pi }\]

    Correct Answer: B

    Solution :

    Velocity of efflux when the hole is at depth h, \[\operatorname{v}\,\,=\,\sqrt{2gh}\]. Rate of flow of water from square hole \[{{Q}_{1}}={{a}_{1}}{{\nu }_{1}}={{L}^{2}}\sqrt{2gy}\] Rate of flow of water from circular hole \[{{\operatorname{Q}}_{2}}=\,\,{{a}_{2}}{{\nu }_{2}}=\,\,\pi {{R}^{2}}\,\sqrt{2g(4y)}\] According to problem \[{{Q}_{1}}={{Q}_{2}}\] \[\Rightarrow \,\,\,{{L}^{2}}\,\sqrt{2gy}\,\,=\,\,4{{R}^{2}}\,\sqrt{2g(4y)}\,\,\,\Rightarrow \,\,R=\frac{1}{\sqrt{2\pi }}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner