How to make a cube topple?(with accuracy)

I have used AddForceAtPosition function for this but when I topple a cube of 5 units it takes a new position which is no at exact 5 units away from previous position.It’s around 5.018 or something like that…
I need a method by which I can place it at exact 5 units away position…

thanking u in advance…

You can configure the accuracy of the PhysX Realtime Physics Engine in Physics Manager: