Reynolds number is the ratio of the inertia force to the
Choose the correct answer
surface tension force
viscous force
gravity force
elastic force
Correct Answer
B. viscous force
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Reynolds number Re = (inertia force) / (viscous force) = rho*V*D/mu = V*D/nu. It determines the flow regime: laminar (Re < 2000), transitional (2000–4000), turbulent (Re > 4000) for pipe flow. Named after Osborne Reynolds (1883). Also governs dynamic similarity in hydraulic model testing: for flow similarity, Re must match between model and prototype. Re = inertia force / viscous force.
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This MCQ belongs to WBPSC AE Previous Years Questions Series. Full tests include timed attempts, rank comparison and subject-wise analysis.