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Question 30937
JEE Physics · Hard

Fluid Mechanics: Viscosity MCQ

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ViscosityHardQuestion 30937

Question

Poiseuille's equation for volume flow rate through a cylindrical pipe is Q = πr⁴ΔP/(8ηL). If radius is halved, flow rate becomes:
  1. A
    Q/2
  2. B
    Q/4
  3. C
    Q/8
  4. D
    Q/16
    Correct

Correct answer

Q/16

Explanation

Q ∝ r⁴. If r → r/2, Q → (1/2)⁴ × Q = Q/16. The r⁴ dependence makes radius critically important.

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