It is desired to design an air plane with a "lift" of $1000 \mathrm{~N}$ per square meter of wing area. If the velocity of streamline flow past the lower wing surface is $100 \mathrm{~m} / \mathrm{s}$, then the required velocity over the upper surface is (given density of air is $1.3 \mathrm{~kg} \mathrm{~m}^{-3}$ )

Equal volume of two immiscible liquids of densities $\rho$ and $2\rho$ are filled in a vessel as shown in figure. Two small holes are punched at depth $\frac{h}{2}$ and $\frac{3h}{2}$ from the surface of lighter liquid. If $v_1$ and $v_2$ are the velocities of efflux at these two holes, then $\frac{v_1}{v_2}$ is

Area of orifice is $a$. Due to ejection of water of density $\rho$ at a constant speed, the equilibrium compression in spring is $x$. The speed of ejection of water is