Water flowing through a pipe of area of cross-section $2 \times 10^{-3} \mathrm{~m}^2$ hits a vertical wall horizontally with a velocity of $12 \mathrm{~ms}^{-1}$. If the water does not rebound after hitting the wall, then the force acting on the wall due to water is

If two soap bubbles $A$ and $B$ of radii $r_1$ and $r_2$ respectively are kept in vacuum at constant temperature, then the ratio of masses of air inside the bubbles $A$ and $B$ is

An aeroplane of mass $4.5 \times 10^4 \mathrm{~kg}$ and total wing area of $600 \mathrm{~m}^2$ is travelling at a constant height. The pressure difference between the upper and lower surfaces of its wings is (Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )