In a test experiment on a model aeroplane in a wind tunnel,the flow speeds on the upper and lower surfaces of the wings are $70 \,m/s$ and $65 \,m/s$ respectively. If the wing area is $2 \,m^2$,the lift of the wing is . . . . . . $N$. (Given density of air $= 1.2 \,kg/m^3$)

$A$ horizontal pipe of non-uniform cross-section allows water to flow through it with a velocity $1 \ m/s$ when the pressure is $50 \ kPa$ at a point. If the velocity of flow has to be $2 \ m/s$ at some other point, the pressure at that point should be: (in $kPa$)

Air streams horizontally past an airplane. The speed over the top surface is $60 \, m/s$ and that under the bottom surface is $45 \, m/s$. The density of air is $1.293 \, kg/m^3$. The difference in pressure is ....... $N/m^2$.

$A$ manometer connected to a closed tap reads $3.5 \times 10^5 \ N/m^2$. When the valve is opened,the reading of the manometer falls to $3.0 \times 10^5 \ N/m^2$. The velocity of the flow of water is ........ $m/s$.

Blood velocity: The flow of blood in a large artery of an anesthetised dog is diverted through a Venturi meter. The wider part of the meter has a cross-sectional area equal to that of the artery,$A = 8 \; mm^2$. The narrower part has an area $a = 4 \; mm^2$. The pressure drop in the artery is $24 \; Pa$. What is the speed (in $m/s$) of the blood in the artery?

Water flows in a horizontal pipe whose one end is closed with a valve. The reading of the pressure gauge attached to the pipe is $P_1$. The reading of the pressure gauge falls to $P_2$ when the valve is opened. The speed of water flowing in the pipe is proportional to