In this figure,an ideal liquid flows through a tube of uniform cross-section. The liquid has velocities $v_A$ and $v_B$,and pressures $P_A$ and $P_B$ at points $A$ and $B$ respectively.

$A$ closed pipe containing liquid showed a pressure $P_1$ by gauge. When the valve was opened, the pressure was reduced to $P_2$. The speed of water flowing out of the pipe is ($\rho$ = density of water).

The lift of an airplane is based on

The figure shows a liquid of given density flowing steadily in a horizontal tube of varying cross-section. The cross-sectional areas at $A$ is $1.5 \, cm^2$,and at $B$ is $25 \, mm^2$. If the speed of the liquid at $B$ is $60 \, cm/s$,then find $(P_A - P_B)$ in $Pa$. (Given: $P_A$ and $P_B$ are liquid pressures at points $A$ and $B$ respectively. Density $\rho = 1000 \, kg/m^3$. $A$ and $B$ are on the axis of the tube.)

What is an aerofoil? Explain.

Which types of energies are present in the streamline flow of an ideal fluid?