Question

What amount of energy will be liberted if 1000 droplets of water each of diameter `10^(-6)` cm. coalesce to from a bigger drop. Surface tension of water is `75xx10^(-3) Nm^(-1)`

Answer 1

Correct Answer - `2.12 xx 10^(-14) J`
Energy realsed ` = S xx[1000xx4 pi r^2 - 4 pi R62]`
Where, ` r = (10^(-6)//2)cm = 0.5 xx 10^(-8) m,`
and `10^3 xx(4)/(3) pi r^3 = (4)/(3)pi R^3`
or `R = 10 r = 10 xx 0.5 xx 10^(-8)m`