Determining inertia of a chunk

Hi,

I'm simulating a rotating chunk with some grippers attached to it. The grippers suddenly grip a component in order to fasten it on a threaded component.

I would like to know the inertia of the chunk, i.e. what's the inertia of the chunk if it suddenly stopped due to the fact that the grippers are gripping a component ?

Here's a pic of the chunk:

I tried to set up a motion study (attched) but I don't know which plot to use to gain this piece of info.

Thanks,

Alex

SolidworksMotion Studies