Center of Mass Versus Tail-end Motion, and Instantaneous Versus Average Velocity
By Dr. Gregory S. Jenkins, Ph.D. Physics (April 11, 2007)
Many people who support the notion that airplanes did not collide with the WTC towers erroneously apply physics to substantiate their claim. The following letter attempts to clarify the difference between the ‘airplane deceleration’ (which can only be well described by the center of mass motion) versus tail deceleration. The concept of average versus instantaneous velocity is also highlighted. I use the airplane impact analysis published by NIST in NCSTAR1-2 and NCSTAR1-2B to vividly illustrate these concepts, and show that NIST clearly reports a 70% decrease in velocity just after the tail section passes through the outer wall, not 0% as alleged by Morgan Reynolds3 and others, representing a net loss in kinetic energy of 91%
