Question

Water flows at a speed of 6 cm s⁻¹ through a tube of radius 1 cm. Coefficient of viscosity of water at room temperature is 0.01 poise. Calculate the Reynolds number. Is it a steady flow? 

Answer 1

Given:
Speed of water, v = 6 cm/s = 6 × 10⁻² m/s
Radius of tube, r = 1 cm = 10⁻² m
Diameter of tube, D = 2 × 10⁻² m
Coefficient of viscosity, η = 0.01 poise

Let the Reynolds number be R and the density of water be ρ.

\[\Rightarrow \text{ R }= \frac{\text{ vp }D}{\eta}\]
\[ = \left( 6 \times {10}^{- 3} \right) \times {10}^3 \times \frac{2 \times {10}^{- 2}}{{10}^{- 2}}\]
\[ = 120\]

Here, the Reynolds number is less than 2000. Therefore, it is a steady flow.