A plane is in level flight at constant speed and each of its two wings has an area of $40 \mathrm{~m}^2$. If the speed of the air is $180 \mathrm{~km} / \mathrm{h}$ over the lower wing surface and $252 \mathrm{~km} / \mathrm{h}$ over the upper wing surface, the mass of the plane is______ $\mathrm{kg}$. (Take air density to be $1 \mathrm{~kg} \mathrm{~m}^{-3}$ and $\mathrm{g}=10 \mathrm{~ms}^{-2}$ )

A tube is attached as shown in closed vessel containing water. The velocity of water coming out from a small hole is :

Water containing air bubbles flows without turbulence through a horizontal pipe which has a region of narrow cross-section. In this region, the bubbles

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

Water flows in a horizontal tube as shown in figure. The pressure of water changes by $600\, N/ m^2$ between $A$ and $B$ where the area of crosssection are $30\, cm^2$ and $15\, cm^2$ respectively. Find the rate of flow of water through the tube.

In the following fig. is shown the flow of liquid through a horizontal pipe. Three tubes $A, B$  and $ C$  are connected to the pipe. The radii of the tubes $A, B $ and $C$  at the junction are respectively $ 2 cm, 1 cm$   and $2 cm.$  It can be said that the