Question

A mercury drop of radius $1cm$ is sprayed into ${10}^6$ drops of equal size. The energy expended in joule is (surface tension of mercury is $460\ast {10}^{-3}$ N / m):

• A. $0.057$
• B. $5.7$
• C. $5.7\times {10}^{-4}$
• D. $5.7\times {10}^{-6}$

Answer 1

The correct option is A $0.057$

$R=1cm,n={10}^6$

$\Delta \bigcup =4\pi R^2(n^{1/3}-1)T$

$=4\pi \times {10}^{-4}({10}^2-1)460\times {10}^{-3}$

$=0.057J$