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Question
A soap bubble of radius 12 cm is blown. Surface tension of soap solution is 30 dyne/cm. Calculate the work done in blowing the soap bubble.
Solution
r = 12 cm, T = 30 dyne/cm, W = ?
Initial surface area of soap bubble = 0
Final surface area ΔA = 2 × 4πr2
∴ Increase in surface area = 2 × 4πr2
∴ Work done W = T × ΔA
= 30 × 8 × 3.14 × (12)2
= 108518.4 erg
= 108518.4 × 10−7
= 1.085 × 10−2 J
The work done in blowing the soap bubble is 1.085 × 10−2 J.
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