Calculate the work done in blowing a soap bubble of diameter 5 cm using a soap solution of surface tension 30 dyn/cm.

Work done w = T.dA  ...where T = surface tension and dA = change in surface area
                       = T . 8 (Pi)R² .......... surface area is twice because for soap there are two films
w = 30 x 8 x 3.14 x 2.5 x2.5
w = 4710 ergs