If water is flowing in a pipe with speed $2 \, m/s$,then its kinetic energy per unit volume is ........... $J/m^3$.

$A$ closed water tank has a cross-sectional area $A$. It has a small hole at a depth of $h$ from the free surface of the water. The radius of the hole is $r$ such that $r \ll \sqrt{\frac{A}{\pi}}$. If $p_o$ is the pressure inside the tank above the water level and $p_a$ is the atmospheric pressure,the rate of flow of the water coming out of the hole is ($\rho$ is the density of water).

Why do two rowing boats moving parallel to each other come closer (attract) to each other?

State Bernoulli's equation in words and write its mathematical formula.

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

The pressure of water in a water pipe when the tap is closed and opened is $3.5 \times 10^5 \, N/m^2$ and $3 \times 10^5 \, N/m^2$ respectively. With the tap open,the velocity of water flowing is ........... $m/s$. (Take density of water $\rho = 10^3 \, kg/m^3$)