1000 drops 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 "=1000rArrn^(1//3)=10, n^(2//3)=100`
`"Surface tension of liquid T"="35 dyne cm"^(-1)`
`"Radius of each small drop r = 2mm = 0.2 cm"`
`"Energy evolved in merging W"=4pir^(2)T[n-n^(2//3)]`
`rArr W=4xx(22)/(7)xx(2xx10^(-1))^(2)35[1000-100]`
`rArrW=(88xx35xx4xx10^(-2))/(7)[900]`
`=15840ergs.~~1.58xx10^(-3)J`