Question

calculate the work done to increase the radius of a soap bubble from 1cm to 3cm.Surface tension of soap solution is 0.072Nm-1

Answer 1

The work done to increase the radius of the soap bubble from 1 cm to 3 cm will be 7.23 x 10⁻⁴ Joules

Explanation :

Initial surface area of the soap bubble

= 4πr²

= 4π x (10⁻²)²

= 4π x 10⁻⁴

Final surface area of the bubble

= 4πR²

= 4π x (3x10⁻²)²

= 36π x 10⁻⁴

Hence change in surface area, ΔA = 36π x 10⁻⁴ - 4π x 10⁻⁴

= 32π x 10⁻⁴

surface tension, T = 0.072 N/m

Hence work done = T x 2ΔA

= 0.072 x 32π x 10⁻⁴

= 7.23 x 10⁻⁴ J

Hence the work done to increase the radius of the soap bubble from 1 cm to 3 cm will be 7.23 x 10⁻⁴ Joules