Question

A 225m long, 300mmϕ concrete pipe and a 400m long, 400mmϕ concrete pipe are connected in series. What is the diameter of a 625m long equivalent pipe?

Answer 1

Explanations & Calculations

• If the equivalent diameter is $\small D,$ then

$\qquad\qquad \begin{aligned} \small \frac{L}{D^5}&=\small \Sigma_{i=1}^2\frac{L_i}{D_i^5}\\ \small \frac{625}{D^5}&=\small \frac{225}{300^5}+\frac{400}{400^5}\\ \small D^5&=\small \frac{625}{1.317}\times100^5\\ \small D&=\small 342.97\\ &\approx\small 343\,mm \end{aligned}$