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MHT CET · Physics · Mechanical Properties of Fluids

A liquid drop of radius ' \(R\) ' is broken into ' \(n\) ' identical small droplets. The work done is \([\mathrm{T}=\) surface tension of the liquid]

  1. A \(4 \pi R^2\left(n^{\frac{2}{3}}-1\right) T\)
  2. B \(4 \pi R^2\left(n^{\frac{1}{3}}-1\right) T\)
  3. C \(4 \pi R^2\left(1-n^{\frac{1}{3}}\right) T\)
  4. D \(4 \pi R^2\left(1-n^{\frac{2}{3}}\right) T\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(4 \pi R^2\left(n^{\frac{1}{3}}-1\right) T\)

Step-by-step Solution

Detailed explanation

Volume of \(\mathrm{n}\) smaller droplets \(=\) Volume of bigger drop
\(\begin{aligned}
& \mathrm{n} \frac{4}{3} \pi \mathrm{r}^3=\frac{4}{3} \pi \mathrm{R}^3 \\
& \therefore \quad \mathrm{R}=\mathrm{n}^{\frac{1}{3}} \cdot \mathrm{r} \\
& \mathrm{r}=\frac{\mathrm{R}}{\mathrm{n}^{\frac{1}{3}}}
\end{aligned}\)
\(\begin{aligned} \text {Work done } W & =\left[n \cdot 4 \pi r^2-4 \pi R^2\right] T \\ & =4 \pi\left[n \cdot \frac{R^2}{n^{\frac{2}{3}}}-R^2\right] T \\ & =4 \pi R^2\left[n^{\frac{1}{3}}-1\right] T\end{aligned}\)