Question

If 8 drops join to form one too and the energy of one drop is 1 j then what is the energy of big drop?

Answer 1

Let r be radius of common drop

$\frac{4}{3} \pi r^{3} = 2*\frac{4}{3} \pi R^{3}$

$r=2^1/3{R}$

surface tension of 2 drops:

$2*4\pi R^{2} T$

surface tension of common drop:

$4\pi r^{2} T$

Ratio:

2*4\pi R^{2} T  

$=\frac{2*4\pi R^{2} T }{4\pi r^{2} T}$

$=\frac{ 2R^{2} }{2^{2/3}R^{2} }$

$=2^{1/3}$