JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2013

  • question_answer
        Water flows along a horizontal pipe whose cross-section is not constant. The pressure is 1 cm of Hg where the velocity is\[35\text{ }cm{{s}^{-1}}\]. At a point where the velocity is\[65\text{ }cm{{s}^{-1}},\]the pressure will be

    A)  0.89 cm of Hg                   

    B)  8.9 cm of Hg

    C)  0.5 cm of Hg                     

    D)  1 cm of Hg

    Correct Answer: A

    Solution :

                     In horizontal pipe \[{{p}_{1}}+\frac{1}{2}pv_{1}^{2}={{p}_{2}}+\frac{1}{2}pv_{2}^{2}\] Here, \[{{p}_{1}}={{p}_{m}}g{{h}_{1}}=13600\times 9.8\times {{10}^{-2}}\]                 \[{{p}_{2}}=13600\times 9.8\times h\]                 \[\rho =1000\,kg{{m}^{-3}}\]                 \[{{v}_{1}}=35\times {{10}^{-2}}m{{s}^{-1}}\]                 \[{{v}_{2}}=65\times {{10}^{-2}}m{{s}^{-1}}\] \[\therefore \]From Eq. (i) \[13600\times 9.8\times {{10}^{-2}}+\frac{1}{2}\times 1000\times {{(0.35)}^{2}}\] \[=13600\times 9.8\times h+\frac{1}{2}\times 1000\times {{(0.65)}^{2}}\] \[=0.86\,cm\,of\,Hg\]


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