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QJEEM24Phc076: JEE Main 2024 Physics - Class 11 JEEM24Phc076 Solution: A small liquid drop of radius is divided into 27 identical…

A small liquid drop of radius RR is divided into 27 identical liquid drops. If the surface tension is TT , then the work done in the process will be:

Multiple Choice Options

  • A 4πR2 T4 \pi \mathrm{R}^2 \mathrm{~T}
  • B 8πR2 T8 \pi R^2 \mathrm{~T}
  • C 18πR2T\frac{1}{8} \pi R^2 T
  • D 3πR2 T3 \pi R^2 \mathrm{~T}

Step-by-Step Verified Solution

Volume constant

amp;43πR3=27×43×πr3amp;R3=27r3amp;R=3ramp;r=R3amp;r2=R29\begin{aligned}& \frac{4}{3} \pi R^3=27 \times \frac{4}{3} \times \pi r^3 \\& R^3=27 r^3 \\& R=3 r \\& r=\frac{R}{3} \\& r^2=\frac{R^2}{9}\end{aligned}

amp; Work done =T.ΔAamp;=27T(4πr2)−T4πR2amp;=27T4πR29−4πR2Tamp;=8πR2T\begin{aligned}& \text { Work done }=T . \Delta A \\& =27 T\left(4 \pi r^2\right)-T 4 \pi R^2 \\& =27 T 4 \pi \frac{R^2}{9}-4 \pi R^2 T \\& =8 \pi R^2 T\end{aligned}

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