- #1

mbrmbrg

- 496

- 2

I have a disk parallel to the floor rotating about an axis perpindicular to the floor, going through the center of the disk.

Its moment of inertia is [tex]I=\frac{1}{2}mR^2[/tex]

I also have a ring (which I will forbear to describe. A picture is worth a thousand words [or 30-ish, in this case], so please see attatchment) with intertia [tex]I=\frac{1}{2}m(R_1^2+R_2^2)[/tex]

All fine and dandy. But when I place one on top of the other (still rotating about the same axis), to find the moment of inertia, do I just add their individual moments? Or something else?

Its moment of inertia is [tex]I=\frac{1}{2}mR^2[/tex]

I also have a ring (which I will forbear to describe. A picture is worth a thousand words [or 30-ish, in this case], so please see attatchment) with intertia [tex]I=\frac{1}{2}m(R_1^2+R_2^2)[/tex]

All fine and dandy. But when I place one on top of the other (still rotating about the same axis), to find the moment of inertia, do I just add their individual moments? Or something else?