1000 drops of a liquid each of diameter 4 mm coalesce to form a single large drop. If surface tension of liquid is 35 `"dyn "cm^(-1)`, calculate the energy evolved by the system in the process.

Explanation

Number of drops n = 1000 `rArrn^(1//3)=10rArrn^(2//3)=100`
Surface tension of liquid T = 35 dyne `cm^(-1)`
Radius of each small drop r = 2 mm = 0.2 cm
Energy evolved in merging
`W=4pir^(2)T[n-n^(2//3)]rArrW=4xx22/7xx(2xx10^(-1))^(2)35[1000-100]`
`rArrW=(88xx35xx4xx10^(-2))/7[900]`
= 15840 ergs. `~~1.58xx10^(-3)J`