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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?
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Solution
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.
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