Water flows through a horizontal pipe of variable cross-section at the rate of $12 \pi$ litre per minute. The velocity of the water at the point where the diameter of the pipe becomes $2 \text{ cm}$ is (in $\text{ m/s}$)

The blades of a windmill sweep out a circle of area $A$. If the wind flows at a velocity $v$ perpendicular to the circle,then the mass of the air of density $\rho$ passing through it in time $t$ is

$A$ shower head has $25$ circular openings, each with radius $1 \,mm$. The shower head is connected to a pipe with radius $2 \,cm$. If the speed of the water in the pipe is $25 \,cm/s$, what is its speed as it exits the shower head openings (in $\,m/s$)?

The cylindrical tube of a spray pump has a cross-section of $8 \,cm^{2}$, one end of which has $40$ fine holes each of area $10^{-8} \,m^{2}$. If the liquid flows inside the tube with a speed of $0.15 \,m \,min^{-1}$, the speed with which the liquid is ejected through the holes is (in $\,ms^{-1}$)

Fountains usually seen in gardens are generated by a wide pipe with an enclosure at one end having many small holes. Consider one such fountain which is produced by a pipe of internal diameter $2 \ cm$ in which water flows at a rate $3 \ ms^{-1}$. The enclosure has $100$ holes each of diameter $0.05 \ cm$. The velocity of water coming out of the holes is (in $ms^{-1}$):

An engine pumps a liquid of density $d$ continuously through a pipe of cross-sectional area $A$. If the speed of the liquid passing through the pipe is $V$,what is the kinetic energy per unit time imparted to the liquid?