$A$ plane is in level flight at constant speed and each of its two wings has an area of $25 \; m^{2}$. If the speed of the air is $180 \; km/h$ over the lower wing and $234 \; km/h$ over the upper wing surface,determine the plane's mass in $kg$. (Take air density to be $1 \; kg \; m^{-3}$ and $g = 9.8 \; m/s^{2}$).

Water is flowing in streamline motion through a horizontal tube. The pressure at a point in the tube is $p$ where the velocity of flow is $v$. At another point, where the pressure is $p/2$, the velocity of flow is (density of water $= \rho$)

$A$ steady flow of a liquid of density $\rho$ is shown in the figure. At point $1$,the area of cross-section is $2A$ and the speed of flow of liquid is $\sqrt{2} \ m \ s^{-1}$. At point $2$,the area of cross-section is $A$. Between the points $1$ and $2$,the pressure difference is $100 \ N \ m^{-2}$ and the height difference is $10 \ cm$. The value of $\rho$ is (Acceleration due to gravity $= 10 \ m \ s^{-2}$) (in $kg \ m^{-3}$)

The velocity of kerosene oil in a horizontal pipe is $5 \ m/s$. If $g = 10 \ m/s^2$,then the velocity head of the oil will be ....... $m$.

What is an aerofoil? Explain.

The reading of a pressure gauge connected to a closed tap is $3.5 \times 10^5 \, N/m^2$. When the tap is opened,the reading of the pressure gauge falls to $3.0 \times 10^5 \, N/m^2$. The velocity of water is ........ $m/s$.