Water is flowing through a horizontal pipe in streamline flow. At the narrowest part of the pipe,

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

At what speed will the velocity head of a stream of water be equal to $40 \ cm$ of $Hg$ (in $cm/sec$)?

Water is pumped through the hose shown below, from a lower level to an upper level. Compared to the water at point $1$, the water at point $2$:

$A$ steady flow of water passes along a horizontal tube from a wide section $X$ to the narrower section $Y$,see figure. Manometers are placed at $P$ and $Q$ at the sections. Which of the statements $A, B, C, D$ is most correct?

An aeroplane of mass $3 \times 10^4 \, kg$ and total wing area of $120 \, m^2$ is in a level flight at some height. The difference in pressure between the upper and lower surfaces of its wings in kilopascals is $(g = 10 \, m/s^2)$.