4) I would explain to the lawyer that the force of the thrower's hand
caused the block to be accelerated and that the resultant N#3 force
from my tooth caused the block to decelerate.
Where is the N#3 force coming from? Is there a cause for it? Is it the
acceleration? The situation seems to have a circular logic to it - although
I find comfort in JD's admonition to simply avoid the question and just go
for description and prediction.