A: Not sure where the factor 0.92 comes from as that look very similar to the rectangular block of uniform density approximation technique from Grime & Jones, You'll see that and other formulas in:
- Yaw Inertia
a section from our currently our of print book McHenry Accident Reconstruction.
The section presents some techniques (including the above referenced Grime/Jones formula) and references some additional papers with approximation techniques.
For msmac licensee, the same information can be found in our msmac Help file- medit3D->Help menu->msmac Input Manual
- see section DISCUSSION: Moment of Inertia
- medit3D->Help menu->msmac Input Manual