The surface tension of a soap solution is 30 dyne/cm. A soap bubble made from this solution has a radius of 1cm. What is the work done in doubling the radius of the soap bubble?

Explanation

For a spap bubble, we multiply the area by 2, as there are two free surfaces
T = dw/dA `therefore dw = T xx dA xx 2 = T xx 4pi (4r^2 - r^2) xx 2`
`dw = 24pir^2T = 24 xx 3.142 xx 1^2 xx 30` = 2262 ergs.