Hello forums!

I think I have a simple problem, but I'm still a Houdini newbie and don't really know how to figure it out.

I've got an a pre-fractured box. I just want a sphere to go through it. However, I ONLY want the pieces that the sphere touches to be activated and react to gravity.

In case it'd be easier to do it in a file I attached a simple scene to start from.

Sorry for the simple question, I've searched here and ODforums and couldn't find an answer. Thanks for any replies!