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Water flows with a speed of 6 cm/s through a tube of radius 1 cm. The coefficient of viscosity of water at room temperature is 0.01 poise. Calculate the Reynolds number for this flow.

1. 1000
2. 120
3. 1200
4. 1400

Correct answer: 1200

Solution

Re = rho*v*D/eta. Using CGS units (rho = 1 g/cc, eta = 0.01 poise, D = 2 cm) gives Re directly.

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