Mechanical Properties Of Fluids Question 2
Question 2 - 2024 (01 Feb Shift 2)
A big drop is formed by coalescing 1000 small droplets of water. The surface energy will become :
(1) 100 times
(2) 10 times
(3) $\frac{1}{100} th$
(4) $\frac{1}{10} th$
Show Answer
Answer: (4)
Solution:
Lets say radius of small droplets is $r$ and that of big drop is $R$
$\frac{4}{3} \pi R^{3}=1000 \frac{4}{3} \pi r^{3}$
$R=10 r$
$U _i=1000\left(4 \pi r^{2} S\right)$
$U _f=4 \pi R^{2} S$
$=100\left(4 \pi r^{2} S\right)$
$U _f=\frac{1}{10} U _i$
