**Effect of Different Cross Sections**

**Second moment of area** (sometimes incorrectly called moment of inertia) is the geometrical property of a plane cross-section which is based on its area and on the distribution of the area.

- The further the material of the section is away from the neutral axis of the section, the larger the second moment of area of the section. Therefore the shape of a cross section will significantly affect the value of the second moment of area.
- The stiffness of a beam is proportional to the second moment of area of the cross-section of the beam.