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JEE Main 2024 (31 Jan, Shift 2) · Terminal Velocity

Terminal Velocity question from JEE Main 2024 (31 Jan, Shift 2)

Q29JEE Main 2024 · 31 JAN · SHIFT 2Medium

Terminal Velocity

A small spherical ball of radius rr, falling through a viscous medium of negligible density has terminal velocity 'vv'. Another ball of the same mass but of radius 2r2r, falling through the same viscous medium will have terminal velocity:

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Answer: (d)

  1. Negligible medium density: v=2r2ρg9ηv = \dfrac{2r^2\rho g}{9\eta} with ρ=m43πr3\rho = \dfrac{m}{\frac{4}{3}\pi r^3}.
  2. So v∝mrv \propto \dfrac{m}{r}; same mass, radius doubled.
  3. v′=v2v' = \dfrac{v}{2}
  4. So the answer is (d) v2\frac{v}{2}.
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