Fluid Mechanics Viscosity Question 124

Question: A viscous fluid is flowing through a cylindrical tube. The velocity distribution of the fluid is best represented by the diagram[BCECE 2005]

Options:

A) $ 4Q $

B) Q

C) $ \frac{Q}{4} $

D) $ \frac{Q}{8} $

Show Answer

Answer:

Correct Answer: D

Solution:

$ V=\frac{\pi pr^{4}}{8\eta l} $ $ V\propto P,r^{4} $ ($ \eta \ \text{and }l $ are constants) \ $ \frac{V_{2}}{V_{1}}=\left( \frac{P_{2}}{P_{1}} \right)\ {{\left( \frac{r_{2}}{r_{1}} \right)}^{4}} $ = $ 2\times {{\left( \frac{1}{2} \right)}^{4}} $ = $ \frac{1}{8} $ \ $ V_{2}=\frac{Q}{8} $