$A$ 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 $g = 9.8 \; m/s^{2}$).

Air streams horizontally past an airplane. The speed over the top surface is $60 \, m/s$ and that under the bottom surface is $45 \, m/s$. The density of air is $1.293 \, kg/m^3$. The difference in pressure is ....... $N/m^2$.

In old age,arteries carrying blood in the human body become narrow,resulting in an increase in blood pressure. This follows from:

If the velocity of flow is $4 \, m/s$,then the velocity head is ......... $m$.

Water from a tap emerges vertically downwards with an initial velocity of $4 \,m/s$. The cross-sectional area of the tap is $A$. The flow is steady and the pressure is constant throughout the stream of water. The distance $h$ vertically below the tap,where the cross-sectional area of the stream becomes $\frac{2}{3} A$,is (take $g = 10 \,m/s^2$): (in $\,m$)

The weight of an aeroplane flying in air is balanced by