The shape factor of a circular section with radius R is
- A4R/3π
- B4R/π
- C16/3πCorrect
- D8/3π
Solution
Concept
Shape factor = Zp / Z
Formula
S = 16/3π ≈ 1.70
Step-by-step solution
1. Z = πR³/4; Zp = 4R³/3. 2. S = Zp/Z = (4/3)/(π/4) = 16/3π ≈ 1.70.
Explanation
The shape factor of a circular section is about 1.70; for a rectangle it is 1.5.
Why the other options are wrong
Options with R are dimensional, and 8/3π is half the right value.
Shortcut
Circle 1.70, rectangle 1.5, I-section about 1.12–1.15.
Common mistake
Mixing constants.
Correct answer: C) 16/3π