Question

please solve this question

Answer 1

We know that energy is the capacity of doing work .

So energy stored in the surface = amount of work done by the tension.

This amount of work = tension × surface area × number of surfaces (of the bubble)

Surface area of sphere = $4\pi r^2$

                                           $\implies 4\times \frac{22}{7}\times(2.1)^2$

                                           $\implies \frac{88}{7}\times 4.41$

                                           $\implies \frac{388.08}{7}$

                                            $\implies 55.44$.......................(1)

Energy stored will be :

                                     $\implies 2\times 4\pi r^2\times 4.5\times10^-^2Nm^-^1$

                                      $\implies 2\times 55.44 \times 4.5\times 10^-^2Nm^-^1$ [From (1)]

                                       $\implies 110.88\times 4.5\times 10^-^2Nm^-^1$

                                       $\implies 498.96 \times 10^-^2 Nm^-^1$

                                        $\implies 4.9896 \times 10^-^4 Nm^-^1$

Hope it helps you:-)

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