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JEE Physics · Hard

Fluid Mechanics: Terminal Velocity MCQ

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Terminal VelocityHardQuestion 30958

Question

In oil of viscosity 5 Pa·s, a 1 mm radius steel sphere (ρ = 8000 kg/m³) falls. Terminal velocity is (ρ_oil = 800 kg/m³, g = 10 m/s²):
  1. A
    3.2×10⁻³ m/s
    Correct
  2. B
    1.56 m/s
  3. C
    0.156 m/s
  4. D
    0.0156 m/s

Correct answer

3.2×10⁻³ m/s

Explanation

vt=2r2(ρs−ρf)g/(9η)=2(10−3)2(7200)(10)/(45)=<strong>3.2×10−3 m/s</strong>v_t=2r^2(ρ_s-ρ_f)g/(9η)=2(10^{-3})^2(7200)(10)/(45)=<strong>3.2×10^{-3}\text{ m/s}</strong>.

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