Q62 / 75 · JEE Main 2025 (24 Jan Shift 1) · Physics

The amount of work done to break a big water drop of radius ' $R$ ' into 27 small drops of equal radius is 10 J . The work done required to break the same big drop into 64 small drops of equal radius will be

  • Correct answer
    A
    15 J
  • B
    5 J
  • C
    20 J
  • D
    10 J

Solution

$\begin{aligned} & W_1=s 4 \pi\left(\frac{R}{3}\right)^2 \times 27-4 \pi R^2 \cdot s \\ & \Rightarrow W_1=4 \pi R^2 \cdot s(2)=10 \text { Joule } \end{aligned}$ Now, $W_2=s 4 \pi R^2(4-1)=4 \pi R^2 s \times 3$ $\Rightarrow \quad W_2=3 \times \frac{10}{2}=15 \text { Joule }$

Hence, the correct answer is option: 'A'.

Relevant Questions