Area Moment of Inertia - Annulus Cross Section

Description

The second moment of area, also known as moment of inertia of plane area, area moment of inertia, polar moment of area or second area moment, is a geometrical property of an area which reflects how its points are distributed with regard to an arbitrary axis.
The second moment of area for a shape is easier to be calculeted with respect to a parallel axis or with respect to a perpendicular axis through the centroid of the shape.
The formula calculates the moment of inertia of a filled annulus cross section with inner radius r1 and outer radius r2 with respect to a horizontal axis through the centroid of the annulus, parallel to the shape. (Parallel axis theorem)