What is the value of Reynolds number for unsteady flow?

Water is conveyed through a uniform tube of $8 \text{ cm}$ in diameter and $3140 \text{ m}$ in length at the rate of $2 \times 10^{-3} \text{ m}^3/\text{s}$. The pressure required to maintain the flow is (Viscosity of water $= 10^{-3} \text{ SI units}$):

What is Reynolds number?

$A$ liquid of density $10^3 \, kg/m^3$ and coefficient of viscosity $8 \times 10^{-2} \, \text{decapoise}$ is flowing in a tube of radius $2 \, cm$ with speed $2 \, m/s$. The Reynold's number is ..........

$Assertion :$ For Reynolds number $Re > 2000$, the flow of fluid is turbulent.
$Reason :$ Inertial forces are dominant compared to the viscous forces at such high Reynolds numbers.

In the case of a fluid flowing on a horizontal surface, the flow of the fluid becomes unsteady when the Reynolds number $(R_n)$ is: