The area moment of inertia, also known as second moment of inertia, moment of inertia of a plane area or second area moment.
The area moment of inertia of a plane area is referred to the second moment of area since the first moment Q is multiplied by the differential area moment arm:
![](https://www.abbottaerospace.com/wp-content/uploads/2019/05/166.png)
Where the elements are integrated over the whole body.
The area moment of inertia about the Z axis (polar moment of inertia) is given by the following expression:
![](https://www.abbottaerospace.com/wp-content/uploads/2019/05/167.png)