Water is moving with a speed of $5.18 \; ms^{-1}$ through a pipe with a cross-sectional area of $4.20 \; cm^2$. The water gradually descends $9.66 \; m$ as the pipe increases in area to $7.60 \; cm^2$. The speed of flow at the lower level is ....... $ms^{-1}$.

$A$ 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

$A$ water spray gun is attached to a hose of cross-sectional area $30 \text{ cm}^2$. The gun comprises $10$ perforations, each of cross-sectional area $15 \text{ mm}^2$. If the water flows in the hose with a speed of $50 \text{ cm/s}$, calculate the speed at which the water flows out from each perforation. (Neglect any edge effects)

The total area of cross-section is $0.25\,m^2$. If the blood is flowing at the rate of $100\,cm^3/s$,then the average velocity of flow of blood through the capillaries is ........ $mm/s$.

Explain the characteristics of streamlines.

$A$ river gradually deepens from a depth of $4 \ m$ to a depth of $8 \ m$ as shown. The width,$W$,of the river does not change. At the depth of $4 \ m$,the river's speed is $12 \ m/s$. Its velocity at the $8 \ m$ depth is ......... $m/s$.