# Formula for inertia

• I
Calculating for a section of an engines connecting rod that is always changing speed
I have seen different formulas for inertia. Must be different types.
Since it is changing speed I guess I am looking for the inertia that is against that change.
any help is much appreciated. I know ya'll get a lot of questions on this forum.

Assuming that you are treating the con rod as a rigid body, the MMOI is simply a constant, the integral of r^2 dm. Changing speed has no impact on the MMOI value.

I think maybe the formula I need is the one that includes velocity which is
KE= .5 x kg x velocity^2

CWatters