The moment of inertia of a hollow circular section about its centroidal axis is:
Where, D = diameter of outer circle
d = diameter of inner circle
1
\(\rm \frac{\pi (d^4+D^4)}{64}\)
2
\(\rm \frac{\pi (D^4-d^4)}{64}\)
3
\(\rm \frac{\pi (d^4+D^4)}{32}\)
4
\(\rm \frac{\pi (D^3-d^3)}{12}\)