a. Slenderness ratio of column is basically defined as the ratio of effective length of the column to the least radius of gyration. Slenderness ratio will be given in numbers because it is one ratio and hence slenderness ratio will not have any unit.

Slenderness ratio is usually displayed by Greek letter λ Slenderness ratio = Effective length of the column/ Least radius of gyration.

b. Radius of Gyration defined as the square root of a ratio of the moment of inertia to the cross-sectional area of the material. It is the measure of slenderness of the area of cross section of the column

Where k is the radius of gyration of the given column A is an area of the cross-section of the column I = Area moment inertia of the given column