Properties of matter 22

Energy of a soap bubble = 2T.4Î R² [as T=E/A and bubble has two surfaces..]
So. energy spent in blowing a soap bubble of radius 7 cm = 2*30*4*22/7*49 = 36960 erg = 0.003696 J

Energy of a soap bubble of double radius = 2T.4Î (2R)² = 147840 erg = 0.014784 J

So, further work done = E₂-E₁ = 110880 erg = 0.011088 J