Q 11-09-020NEETJEE MainMedium
A steel ball of radius $1$ mm moves at $0.1$ m s$^{-1}$ through glycerine of viscosity $1.5$ Pa s. The viscous drag on it is about
Answer: (C) $2.8 \times 10^{-3}$ N
Concept. Stokes's law: $F = 6\pi\eta rv$.
Step 1. Substitute. $6\pi \times 1.5 \times 10^{-3} \times 0.1 \approx 2.8 \times 10^{-3}$ N.
Answer. $2.8 \times 10^{-3}$ N (Option C).
Solution by Sreeraj P, M.Sc Physics