Select the correct statement regarding streamline flow.

Explain the concept of a tube of flow.

$A$ tube of length $L$ is shown in the figure. The radius of the cross-section at point $(1)$ is $2 \ cm$ and at point $(2)$ is $1 \ cm$. If the velocity of water entering at point $(1)$ is $2 \ m/s$,then the velocity of water leaving at point $(2)$ will be: (in $m/s$)

Water is flowing continuously from a tap having an internal diameter $8 \times 10^{-3} \ m$. The water velocity as it leaves the tap is $0.4 \ m/s$. The diameter of the water stream at a distance $2 \times 10^{-1} \ m$ below the tap is close to .......$\times 10^{-3} \ m$.

What is the effect on the velocity of a fluid if streamlines are closely spaced?

What is a tube of flow?