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Question
Calculate the work done in blowing a soap bubble to a radius of 1 cm. The surface tension of soap solution is 2.5 × 10−2 N/m.
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Solution
Given:
T = 2.5 × 10−2 N/m, r1 = 0 m, r2 = 1 cm = 10−2 m, W = ?
Formula:
W = T dA
= T (2 × 4π r2 − 0)
= T × 8 π r2
= 2.5 × 10−2 × 8 × π × (10−2)2
= 2.5 × 8 × 3.14 × (10−2)2
= 6.275 × 10−5 J
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