What is a tube of flow?

Water is flowing in a pipe of diameter $4 \text{ cm}$ with a velocity $3 \text{ m/s}$. The water then enters into a tube of diameter $2 \text{ cm}$. The velocity of water in the other pipe is .......... $\text{m/s}$.

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?

Explain the characteristics of streamlines.

The Bhagirathi and the Alaknanda merge at Deoprayag to form the Ganga. The speeds of the Bhagirathi and the Alaknanda are in the ratio $1: 1.5$. The cross-sectional areas of the Bhagirathi,the Alaknanda,and the Ganga are in the ratio $1: 2: 3$. Assuming streamline flow,the ratio of the speed of the Ganga to that of the Alaknanda is

Derive the equation of continuity for the steady flow of an incompressible fluid.