### Area Moment of Inertia

The*area moment of inertia*is the second moment of an area around a given axis:

*mass moment of inertia*in §B.4.4 above, we see that mass is replaced by area in the area moment of inertia. In a planar mass distribution with total mass uniformly distributed over an area (

*i.e.*, a constant mass density of ), the mass moment of inertia is given by the area moment of inertia times mass-density :

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