Moment of inertia is the rotational analogue to mass. The moment of inertia must be specified with respect to a chosen axis of rotation. The symbols

**Ixx**,**Iyy**and Izz are frequently used to express the moments of inertia of a 3D rigid body about its three axis.Besides, what is 1st moment of inertia?

From Wikipedia, the free encyclopedia. The

**first moment**of area, sometimes misnamed as the**first moment of inertia**, is based in the mathematical construct**moments**in metric spaces, stating that the**moment**of area equals the summation of area times distance to an axis [Σ(a × d)].What is the unit of second moment of area?

The

**second moment of area**is used to predict deflections in beams. It is denoted by I and is different for different cross sections, for example rectangular, circular, or cylindrical. The unit for this**measure**is length (in mm, cm, or inches) to the fourth power, i.e. mm^{4}or ft^{4}.What is the moment of inertia of a beam?

"Area

**Moment of Inertia**" is a property of shape that is used to predict deflection, bending and stress in**beams**. "Polar**Moment of Inertia**" as a measure of a**beam's**ability to resist torsion - which is required to calculate the twist of a**beam**subjected to torque.