If the work done in blowing a soap bubble of volume ' V ' is ' W ', then the work done in blowing a soap…

If the work done in blowing a soap bubble of volume ' V ' is ' W ', then the work done in blowing a soap bubble of volume ' 2 V ' will be
  1. W
  2. 2 W
  3. $\mathrm{w} \sqrt{2}$
  4. $\quad \mathrm{W}(4)^{\frac{1}{3}}$

Solution

The work done is given as $\mathrm{W}=\mathrm{T} \Delta \mathrm{A}$ Volume of sphere is $V=\frac{4}{3} \pi \mathrm{r}^3$ Area of sphere is $\mathrm{A}=4 \pi \mathrm{r}^2$ $\begin{array}{ll} \therefore & \mathrm{A} \propto \mathrm{~V}^{\frac{2}{3}} \\ \therefore & \mathrm{~W} \propto \mathrm{~V}^{\frac{2}{3}} \end{array}$ $\begin{aligned} & \frac{\mathrm{W}^{\prime}}{\mathrm{W}}=\frac{\mathrm{V}^{\frac{2}{3}}}{\mathrm{~V}^{\frac{2}{3}}} \\ & \frac{\mathrm{~W}^{\prime}}{\mathrm{W}}=\frac{(2 \mathrm{~V})^{\frac{2}{3}}}{\mathrm{~V}^{\frac{2}{3}}} \\ \therefore \quad \frac{\mathrm{~W}^{\prime}}{\mathrm{W}} & =2^{\frac{2}{3}}=4^{\frac{1}{3}} \\ \therefore \quad \mathrm{~W}^{\prime} & =4^{\frac{1}{3}} \mathrm{~W}\end{aligned}$ $\ldots(\because \mathrm{V}=2 \mathrm{~V})$

Asked in: MHT CET 2024 (15 May Shift 2)

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