How does someone make an item stay in place (Floating with no physics) until move it has been moved by physics?

I was thinking of making an explosion for a block world and I only want the blocks to move if they are being blown up (Really New To Code and Unity in general) (Shorter Version I want to take chunks out of my blocky terrain and have some pieces go flying)

if you want the GUI way use a rigid body and enable it through a script. without that rigid body most objects stay in place.