Q 11-09-026NEETJEE MainHard
A liquid drop of radius $R$ and surface tension $T$ is split into $1000$ identical small drops. The work done is
Answer: (D) $36\pi R^2T$
Concept. Work $= T \times$ increase in surface area; volume is conserved.
Step 1. Small radius. $1000r^3 = R^3 \Rightarrow r = \dfrac{R}{10}$.
Step 2. Area increase. $1000 \times 4\pi\dfrac{R^2}{100} - 4\pi R^2 = 36\pi R^2$.
Step 3. Work. $W = 36\pi R^2T$.
Answer. $36\pi R^2T$ (Option D).
Solution by Sreeraj P, M.Sc Physics