Question

The hydraulic mean radius of a circular sewer of diameter \(D\) is given by

• A. \(\dfrac{D}{4}\)
• B. \(\dfrac{D}{2}\)
• C. \(\dfrac{D}{3}\)
• D. \(\dfrac{D}{6}\)

Hint:

Hydraulic mean radius: \[ \boxed{ R=\frac{A}{P} } \] For a full circular pipe, \[ \boxed{ R=\frac{D}{4}. } \]

Answer 1

The Correct Option is A

Step 1: Recall the hydraulic mean radius. Hydraulic mean radius is defined as \[ R=\frac{A}{P}, \] where - \(A\) = Flow area - \(P\) = Wetted perimeter.

Step 2: Calculate for a full circular sewer. For a full circular sewer, \[ A=\frac{\pi D^2}{4}, \] \[ P=\pi D. \] Hence, \[ R=\frac{\pi D^2/4}{\pi D} =\frac{D}{4}. \] Therefore, \[ \boxed{\frac{D}{4}} \] is the correct answer. Hence, \[ \boxed{(A)} \] is the correct answer.