Question

A 225 m long , 300 mm diameter concrete pipe and 400 m long, 500 mm diameter concrete pipe are connected in series. The diameter of 625 m long equivalent pipe is :

• A. 280 mm
• B. 320 mm
• C. 360 mm
• D. 410 mm

Answer 1

The correct option is C 360 mm

$L_1=225m,L_2=400m,D_1=300mm,D_2=500mm,L=625m$

Equivalent pipe has a diameter

$\frac{L}{D^5}=\frac{L_1}{D_1^5}+\frac{L_2}{D_2^5}$

$\frac{625}{D^5}=\frac{225}{{300}^5}+\frac{400}{{500}^5}$

$D=358.6mm=360mm$