BCECE Engineering BCECE Engineering Solved Paper-2008

  • question_answer
    At what speed, the velocity head of water is equal to pressure head of 40 cm of Hg?

    A)  10.3 m/s             

    B)         2.8 m/s

    C)  5.6 m/s               

    D)         8.4 m/s

    Correct Answer: A

    Solution :

    Bernoullis equation for flowing liquid be written as \[p+\frac{1}{2}\rho {{v}^{2}}+\rho gh=\text{constant}\]                               ...(i) Here, \[p=\]pressure energy per unit volume of liquid \[\rho =\]density of liquid (water) \[h=\]height of liquid column \[v=\]velocity of liquid and \[g=\]acceleration due to gravity Dividing the Eq. (i) by \[\rho g,\]we have \[\frac{p}{\rho g}+\frac{{{v}^{2}}}{2g}+h=\text{constant}\] In this expression, \[\frac{{{v}^{2}}}{2g}\]is velocity head and \[\frac{p}{\rho g}\] is pressure head. It is given that, Velocity head = pressure head ie,           \[\frac{{{v}^{2}}}{2g}=\frac{p}{\rho g}\] or            \[{{v}^{2}}=\frac{2P}{\rho }\] or            \[=\frac{2\times 13.6\times {{10}^{3}}\times 40\times {{10}^{-2}}\times 9.8}{{{10}^{3}}}\] \[\therefore \]  \[v=10.32\,m/s\]


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