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JEE Main202624 January 2026Evening ShiftPhysicsMechanical Properties of FluidsActual

A soap bubble of surface tension 0.04 ~N / m is blown to a diameter of 7 cm. If (15000-x) J of work is done in blowing it further to make its diameter 14 cm, then the value of x is _ _ _ _ . ( =22 / 7 )

Correct answer

0

Step-by-step solution

Soap bubble has two surfaces. Work done: W = A Initial radius: r_i = 3.5 cm = 0.035 m, Final radius: r_f = 7 cm = 0.07 m Change in surface area (both surfaces): A = 8 (r_f^2 - r_i^2) = 8 (0.07^2 - 0.035^2) A = 8 (0.0049 - 0.001225) = 8 0.003675 = 0.0294 m² W = 0.0294 0.04 = 0.001176 J = 0.001176 22 7 = 0.003696 J = 3696 μJ Therefore: x = 15000 - 3696 = 11304

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