Two horizontal pipes A and B of equal length carry the same incompressible liquid…
PHYSICS · Single correct · CBSE · Physics · Mechanical Properties of Fluids · Mechanical Properties of Fluids
Problem
Two horizontal pipes A and B of equal length carry the same incompressible liquid under the same pressure difference. Pipe A has an internal diameter of 2 cm while pipe B has 4 cm. Ignoring changes in temperature and surface roughness, which statement about the likelihood of turbulence is correct?
(a) Flow in pipe A will become turbulent first because its smaller diameter produces a higher average speed, raising the Reynolds number sooner.
(b) Both pipes will reach turbulence at the same time because the critical Reynolds number for a given fluid is the same irrespective of pipe diameter.
(c) Flow in pipe B will become turbulent first because it has both a higher average speed and a lower critical speed.
(d) Flow in pipe A will become turbulent first because the critical speed is inversely proportional to diameter, making it lower for the narrow pipe.