"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.
In this regard, 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 Ixx and Iyy?
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.
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. mm4 or ft4.