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

Explanation

No. of drops `n=1000impliesn^((1//3))=10,n^((2//3))=100`
Surface tension of liquid `T=35` dyne `cm^(-1)`
Radius of each small drop `r=2mm=0.2m`
Energy evolved in merging `W=4pir^(2)T[n-n^(2//3)]`
`impliesW=4xx(22)/(7)xx(2xx10^(-1))^(2)35[1000-100]`
`impliesW=(88xx35xx4xx10^(-2))/(7)[900]`
`=15840ergsapprox1.58xx10^(-3)J`