Q 11-09-021JEE MainMedium
Water (density $1000$ kg m$^{-3}$, viscosity $10^{-3}$ Pa s) flows at $0.1$ m s$^{-1}$ through a pipe of diameter $2$ cm. Find the Reynolds number of the flow.
Numerical value type. Enter your answer.
Answer: 2000
Concept. Reynolds number $Re = \dfrac{\rho vD}{\eta}$.
Step 1. Substitute.
$$Re = \frac{1000 \times 0.1 \times 0.02}{10^{-3}} = 2000$$
(Close to the onset of turbulence.)
Answer. $2000$.
Solution by Sreeraj P, M.Sc Physics