Write Bernoulli’s equation in formula and in words.

Correct Bernoulli's equation is (symbols have their usual meaning) :

Why free surface of liquid tend to contract their surface ?

Figure shows a siphon. Choose the wrong statement:

($P_0$ = atmospheric pressure)

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 $\mathrm{g}=10 \mathrm{~ms}^{-2}$ )

The Pitot tube shown in the figure is used to measure fluid flow velocity in a pipe of cross sectional area $S$. It was invented by a French engineer Henri Pitot in the early $18^{th}$ century. The volume of the gas flowing across the section of the pipe per unit time is (The difference in the liquid columns is $\Delta h,  \rho_0$ and  $\rho$  are the densities of liquid and the gas respectively) :-