The surface tension of a soap solution is 0.030N/m. What is the energy needed to increase the radius of the soap bubble from 4cm to 6cm.

Explanation

`W = 2 xx T xx [4piR_2^2 - 4piR_1^2]`
= `8piT [R_2^2 - R_1^2]`
= `8 xx 3.14 xx 30 xx 10^-3 [36 -16] xx 10^-4`
= `240 xx 3.14 xx 20 xx 10^-2`
= `150 xx 10^-5 = 1.5 xx 10^-3 J`