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MHT CET202620 April 2026Morning ShiftPhysicsMechanical Properties of FluidsActual

If 450 erg of work is done in blowing a soap bubble of radius ' r ', the additional work required to be done to blow it to a radius equal to 3r is

Options

  1. A2400 erg
  2. B3000 erg
  3. C3600 erg
  4. D4000 erg

Correct answer

C. 3600 erg

Step-by-step solution

Work done in blowing a soap bubble of radius r is W₁ = 2 4 r^2 T = 8 r^2 T Given W₁ = 450 erg. Work done in blowing a soap bubble of radius 3r is W₂ = 2 4 (3r)^2 T = 9 8 r^2 T = 9 W₁ The additional work required to blow it from radius r to 3r is W = W₂ - W₁ = 9 W₁ - W₁ = 8 W₁ W = 8 450 = 3600 erg Answer: 3600 erg

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