Question

Calculate the energy spent in spraying a drop of mercury of $r=1cm$ radius into $N={10}^6$ droplets all of same size. If the surface tension of mercury is $T=35\times {10}^{-3}N/m$.

Answer 1

initial potential energy=TA=35x${10}^{-}3$ x 4x3.14x$1^2$=439.6x${10}^{-}3$=0.4396joules

since the volume remains the same,

therefore, (4/3)x3.14x$1^3$=${10}^6$x(4/3)x3.14x${r}^3

On solving, we get,

r=1/${10}^2$ cm

final potential energy= ${10}^6$ x Tx4x3.14x${0.01}^2$=43.96 joules

So the energy expanded= final potential energy-initial potential energy

=43.96-0.4396=45.5204 joules