**Reynolds number** is used to distinguish:
- Heat from work
- Laminar (streamline) from turbulent flow
- Different liquids by density
- Static from dynamic friction
Show answer and solution
Correct answer: B. Laminar (streamline) from turbulent flow
Reynolds number $R_n = \rho v d / \eta$ (dimensionless).
$R_n < 1000$: laminar
$1000 < R_n < 2000$: transitional
$R_n > 2000$: turbulent flow.