GATE 2025 MT – Question 33
For an application where the Reynolds number is to be kept constant, a liquid with a density of 1 g cm−3 and viscosity 0.01 Poise results in a characteristic speed of 1 cm s−1. If this liquid is replaced by another with a density of 1.25 g cm−3 and viscosity of 0.015 Poise, the characteristic velocity will be ______ cm s−1 (rounded off to one decimal place). Assume the characteristic length of the flow to be the same in both cases.
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Correct answer: 1.2 to 1.2
Explanation
Re=ρvL/μ. Equal characteristic lengths and Reynolds numbers require v2=v1(μ2/μ1)(ρ1/ρ2). Substitution gives 1×(0.015/0.01)×(1/1.25)=**1.2 cm/s**.