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

Question

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

Accepted Answer

Correct answer: 11304. (11304) 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 m^2 W=0.0294 0.04=0.001176 J=0.001176 227=0.003696 J=3696 JTherefore: x=15000-3696=11304

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

Solution

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