The Reynolds number of a flow is the ratio of

$A$ liquid flows through a pipe with a pressure difference of $P$. What should be the pressure difference required to maintain the same flow rate if the radius is doubled and the length is doubled?

The rate of steady volume flow of water through a capillary tube of length $l$ and radius $r$,under a pressure difference of $p$ is $V$. This tube is connected with another tube of the same length but half the radius,in series. Then,the rate of steady volume flow through them is (The pressure difference across the combination is $p$.)

What is turbulent flow? Give an example of turbulent flow.

$A$ flow of liquid is streamline if the Reynolds number is

What is inertial force in the context of fluid dynamics?