The area moment of inertia is the second moment of an area
around a given axis:
where
Comparing with the definition of 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
: