Question

A circular pipe of diameter 0.5 m carries the discharge of 50 l/s. The head loss due to friction in pipe is 0.15 m and friction factor for the pipe is given as 0.01. What is the length (m) of pipe?

• A. 50.5
• B. 85.71
• C. 98.95
• D. 110.01

Answer 1

The correct option is B 85.71

As per Darcy's Weisbach equation

$h_L=\frac{fl{V}^2}{2gD}=\frac{8fl{Q}^2}{{\pi }^{2}g{D}^5}$

$h_L=0.15=\frac{8\times 0.04\times l\times (50\times {10}^{-3}{)}^2}{{\pi }^2\times 9.81\times (0.5{)}^5}$

$l=\frac{0.15\times {\pi }^2\times 9.81\times (0.5{)}^5}{8\times 0.01\times (50\times {10}^{-3}{)}^2}$

$=2269.24m$