Two light balls are suspended as shown in the figure. When a stream of air passes through the space between them,the distance between the balls will

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

Rank in order, from highest to lowest, the liquid heights $h_a$ to $h_d$. The air flow is from left to right. The liquid columns are not drawn to scale.

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 $\,m$)

$A$ fully loaded Boeing aircraft has a mass of $3.3 \times 10^5 \text{ kg}$. Its total wing area is $500 \text{ m}^2$. It is in level flight with a speed of $960 \text{ km/h}$. Estimate the pressure difference between the lower and upper surfaces of the wings.

The flow speeds of air on the lower and upper surfaces of the wing of an aeroplane are $v$ and $2v$ respectively. The density of air is $\rho$ and the surface area of the wing is $A$. The dynamic lift on the wing is: