# Polar Moment of Area - 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 is typically denoted with either an for an axis that lies in the plane or with a for an axis perpendicular to the plane.

In the field of structural engineering, the second moment of area of the cross-section of a beam is an important property used in the calculation of deflection.

## Variables

J | polar moment of area (mm^{4}) |

π | pi |

r_{2} | outer radius (mm) |

r_{1} | inner radius (mm) |