Velocity of WTC 1 upper block without trendline
The areas Boloboffin points to are not decelerations. A deceleration requires a negative slope. Arrow 1 points to an area which is only a little lower acceleration with velocity still increasing. Arrow 2 points to an area which has constant velocity.
These two points do not constitute a jolt or impulse, which requires real deceleration and a loss or drop in velocity.
At all points on the curve the velocity is increasing except for point 2 where it is constant for about 100 milliseconds. Bear in mind that this curve represents a drop of about 100 feet or eight stories, where no deceleration was observed.
To generate a dynamic load sufficient to cause a collapse in the twin towers the velocity drop would have been severe. The fact that there is no velocity drop whatsoever is very telling of what actually occurred.