Fluid Mechanics Viscosity Question 312
Question: A certain number of spherical drops of a liquid of radius ‘r’ coalesce to form a single drop of radius ‘R’ and volume ‘V’. If ‘T’ is the surface tension of the liquid, then:
Options:
A) $ energy=4VT\left( \frac{1}{r}-\frac{1}{R} \right)isreleased $
B) $ energy=3VT\left( \frac{1}{r}+\frac{1}{R} \right)isabsorbed $
C) $ energy=3VT\left( \frac{1}{r}-\frac{1}{R} \right)isreleased $
D) Energy is neither released nor absorbed
Show Answer
Answer:
Correct Answer: C
Solution:
[c] As surface area decreases so energy is released. Energy released$ =4\pi R^{2}T[{{n}^{1/3}}-1] $ (where$ R={{n}^{1/3}}r $ ) $ =4\pi R^{3}T\left[ \frac{1}{r}-\frac{1}{R} \right]=3VT\left[ \frac{1}{r}-\frac{1}{R} \right] $
BETA
