For a circular column having its ends hinged, the slenderness ratio is 160. The l/d ratio of the column is

ANS:C - 40

Correct Answer = A (according to me).

Slenderness ratio = L(eff)/r,
L(eff)=L; since both ends are hinged.
r=radius of gyration.
For hollow cylinder,
mk ^2 = moment of inertia for hollow cylinder,
k =radius of hollow cylinder,
So, for point mass at a distance r(radius of gyration), a moment of inertia = mr^2.
Therefore mk^2 = mr^2.
k = r.
Therefore, l/r=160
l/k=160,
2l/d=160,
l/d=80.