Question

A ${16cm}^3$ volume of water flows per second through a capillary tube of radius r cm and of length 1 cm, when connected to a pressure head of h cm of water. If a tube of the same length and radius r/2 is connected to the same pressure head, find the mass of water flowing per minute through the tube

• A. 80 gram/min
• B. 70 gram/min
• C. 60 gram/min
• D. 50 gram/min

Answer 1

Answer: (C)

60 gram/min

$V\propto \frac{P{r}^4}{l}$

$\frac{v_2}{v_1}={\left(\frac{r/2}{r}\right)}^4$

$\frac{v_2}{16}=\frac{1}{16}$

$v_2=1c{m}^3$per sec

$v_2=60c{m}^3$per min

Mass of water flowing per minute $=v_2\times d=60\times 1=60gram/min$

Hence option 'C' is correct.