Two pipes of radii $2 \, cm$ and $4 \, cm$ are connected in series. What is the ratio of the flow velocities of the fluid in these pipes?

The cylindrical tube of a spray pump has a cross-section of $8.0 \; cm^{2}$,one end of which has $40$ fine holes each of diameter $1.0 \; mm$. If the liquid flow speed inside the tube is $1.5 \; m \, min^{-1}$,what is the speed (in $m/s$) of ejection of the liquid through the holes?

$A$ pipe having an internal diameter $D$ is connected to another pipe of the same size. Water flows into the second pipe through $n$ holes,each of diameter $d$. If the water in the first pipe has speed $v$,the speed of water leaving the second pipe is

Two water pipes $P$ and $Q$ having diameters $2 \times 10^{-2} \ m$ and $4 \times 10^{-2} \ m$,respectively,are joined in series with the main supply line of water. The velocity of water flowing in pipe $P$ is

Explain critical speed,white water rapids,and turbulent flow.

Two water pipes $P$ and $Q$ having diameters $2 \times 10^{-2} \, m$ and $4 \times 10^{-2} \, m$ respectively are joined in series with the main supply line of water. The velocity of water flowing in pipe $P$ is ........