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Consider a cylindrical tank of radius 1 \mathrm{~m} is filled with water. The top surface of water is at 15 \mathrm{~m} from the bottom of the cylinder. There is a hole on the wall of cylinder at a height of 5 \mathrm{~m} from the bottom. A force of 5 \times 10^{5} \mathrm{~N} is applied an the top surface of water using a piston. The speed of ifflux from the hole will be : (given atmospheric pressure \mathrm{P}_{\mathrm{A}}=1.01 \times 10^{5} \mathrm{~Pa}, density of water \rho_{\mathrm{W}}=1000 \mathrm{~kg} / \mathrm{m}^{3} and gravitational acceleration \mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2} )

Option: 1

11.6\: \mathrm{m/s}


Option: 2

10.8\: \mathrm{m/s}


Option: 3

17.8\: \mathrm{m/s}


Option: 4

14.4\: \mathrm{m/s}


Answers (1)

\mathrm{h_1 =15 \mathrm{~m} }

\mathrm{h_2 =5 \mathrm{~m} }
From Eq of Continuity

\mathrm{A_1 V_1 =A_2 V_2 }

\mathrm{V_1=\left(\frac{A_2}{A_1}\right) V_2}

reference level

Applying Bernoulli's equation at \mathrm{pt} (1) & (2)

\mathrm{P_1+\frac{1}{2} \rho v_1^2+\rho g h_1=P_2+\frac{1}{2} \rho v_2^2+\rho g h_2}

\mathrm{\frac{5 \times 10^5}{\pi(1)^2}+0+\rho g h_1=1.01 \times 10^5+\frac{1 }{2}\rho v_{2}^2+\rho g\left ( h_{2} \right )}

\mathrm{v_1<<v_2 \quad\left(A_1 \gg A_2\right)}

\mathrm{\left(\frac{5}{\pi}-1.01\right) \times 10^5+10^5=500 v_2^2}

\mathrm{\frac{4.686}{\pi} \times 10^5=500 \mathrm{~V}_2^2}

\mathrm{\quad V_2=17.8 \mathrm{~m} / \mathrm{s} }

Hence 3 is correct option.









 

Posted by

Sumit Saini

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