The cylindrical tube of a spray pump has radius $R,$ one end of which has $n$ fine holes,each of radius $r.$ If the speed of the liquid in the tube is $v,$ the speed of the ejection of the liquid through the holes is

Water is flowing through two horizontal pipes of different diameters which are connected together. The diameters of the two pipes are $3\, cm$ and $6\, cm$ respectively. If the speed of water in the narrower pipe is $4\, m/s$ and the pressure is $2.0 \times 10^4\, Pa$,then the speed of water in the wider pipe is ........ $m/s$.

$A$ horizontal tube of non-uniform cross-section has radii of $0.1 \,m$ and $0.05 \,m$ respectively at $M$ and $N$. For a streamline flow of an incompressible liquid, the rate of liquid flow is

$A$ laminar stream is flowing vertically down from a tap of cross-section area $1 \ cm^2$. At a distance $10 \ cm$ below the tap,the cross-section area of the stream has reduced to $0.5 \ cm^2$. The volumetric flow rate of water from the tap is about ........ $litre/min$.

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.