When a fluid passes through a constricted part of a pipe, what happens to its velocity and pressure?

Write the limitations and uses of Bernoulli's equation.

$A$ liquid of density $750\,kg\,m^{-3}$ flows smoothly through a horizontal pipe that tapers in cross-sectional area from $A_{1} = 1.2 \times 10^{-2}\,m^{2}$ to $A_{2} = \frac{A_{1}}{2}$. The pressure difference between the wide and narrow sections of the pipe is $4500\,Pa$. The rate of flow of liquid is . . . . . . $\times 10^{-3}\,m^{3}\,s^{-1}$.

$A$ streamline flow of a liquid of density $\rho$ is passing through a horizontal pipe of cross-sectional area $A_1$ and $A_2$ at two ends. If the pressure of the liquid is $P$ at a point where the flow speed is $v$,then the pressure at another point where the flow speed becomes $3v$ is:

Pressure head in Bernoulli's equation is

Why does a flag (or ensign) flutter when there is strong wind? Explain.