1.

The radius of a soap bubble is increased from `(1)/(sqrtpi)` cm to `(2)/(sqrtpi)` cm. If the surface tension of water is `30dynes` per cm, then the work done will beA. 180 ergsB. 360 ergsC. 720 ergsD. 960 ergs

Answer» Correct Answer - C
`W=8piT(r_2^2-r_1^2)=8piT[((2)/(sqrtpi))^2-((1)/(sqrtpi))^2]`
`W=8xxpixx30xx(3)/(pi)=720erg`


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