Question

The correct formula of critical velocity $\left(V_c\right)$ is :

• A. $V_c=\frac{k\eta d}{r}$
• B. $V_c=\frac{k\eta }{dr}$
• C. $V_c=\frac{dr}{k\eta }$
• D. $V_c=\frac{r\eta }{dk}$

Answer 1

Answer: (B)

$V_c=\frac{k\eta }{dr}$

The critical velocity depends on coefficient of viscosity $\eta$, density of the liquid $d$, and radius of the tube $r$ as given by
$V_c=\frac{k\eta }{dr}$ where $k$ is the constant of proportionality.