Question

two small bubble mixed and make a big bubble,then the big bubble's volume make V and surface area make A,air pressure is P and soap water 's surface tension is T ,than what is the right equation a) 4PV+ 3 TA= 0 b)3PV-4TA=0 c) 4PV -3TA= 0 d) 3PV+4TA=0

Answer 1

Heya

Your  answer is,

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Let the radius of two smaller soap bubble is r and larger bubble is R, than we know that 
Surface tension

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T=P(R3−2r3)(4(2r2−R2)T=P(R3−2r3)(4(2r2−R2)
1 more way,
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T=3PδV−4δAT=3PδV−4δA
where  V  &  VA  are  the  change  in  volume  and  surface  area. Therefore, :)

3PδV+4TδA=03PδV+4TδA=0
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This is the answer!
_____________________Hope it helps:)