Quick strange thingy -

If an object is thrown in the air and then comes down upon itself - at its peak it has stopped for a split second.

Well if a fly is flying along a train track in one direction and the train is coming in the opposite direction. When they meet the fly must go through zero in order to reverse its direction - if the train and fly are both together at that point then the train must be stopped at that moment in time (only for a split second) - how can a fly stop a train???

Rob