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

Explain critical speed,white water rapids,and turbulent flow.

Water enters through end $A$ with speed $v_1$ and leaves through end $B$ with speed $v_2$ of a cylindrical tube $AB$. The tube is always completely filled with water. In case $I$,the tube is horizontal; in case $II$,it is vertical with end $A$ upwards; and in case $III$,it is vertical with end $B$ upwards. We have $v_1 = v_2$ for:

$A$ gardening pipe having an internal radius '$R$' is connected to a water sprinkler having '$n$' holes each of radius '$r$'. The water in the pipe has a speed '$v$'. The speed of water leaving the sprinkler is

An incompressible fluid flows steadily through a cylindrical pipe which has radius $2r$ at point $A$ and radius $r$ at point $B$ further along the flow direction. If the velocity at point $A$ is $v$,what is its velocity at point $B$?

An ideal fluid flows (laminar flow) through a pipe of non-uniform diameter. The maximum and minimum diameters of the pipe are $6.4 \; cm$ and $4.8 \; cm,$ respectively. The ratio of the minimum and the maximum velocities of the fluid in this pipe is: