Theory Round 2  
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Diagram shows a vertical bar of length h and width b. The centroid is centered on the vertical bar along the c axis. A parallel horizontal line is at a distance d below the c axis. A caption at the bottom below the parallel horizontal line reads: any axis parallel to centroidal axis c.

The equation

gives the moment of inertia of a rectangle about its own centroidal axis (axis c in the sketch).

Often, we must compute the moment of inertia of this area about some other axis, one that is parallel to the area's centroidal axis c.

Denote the perpendicular distance between the two axes as d.

Here is Canvas object wihch demonstrate the problem.