So it would appear that the geek factor of the prof is inversely proportional to the velocity of the punch. Thus in the limit as x approaches infinity, where x = geek factor, v approaches zero.
I also believe that if the prof is wearing glasses there is an additional time delay factor based on where the water cup hits. He will need some time to adjust the specs while he begins to line up the fist to deliver the blow or attempt at delivery, as the case may be.
Ain't physics phun?