by Rick Rajter
October 26, 2006
from NoMoreGames Website
To the layman, these two conservation laws mean we should expect TWO major sources of slowdown when one object penetrates another:
A quick example: If I throw a baseball through a window, the dissipation of energy occurs in breaking the big piece into little pieces and velocity gained by little pieces as they fly away from the original window location. The kinetic energy of the ball is a finite supply used up as these two processes occur. At UA flight 175's alleged impact speeds (estimated anywhere between 500-600 mph depending upon the source), a 767 speeding at reasonably full weight would have some 4 billion joules of KE (kinetic energy) for consideration.
To the best of our knowledge, Stefan Grossman (presumably helped by Marcus Icke) did the first numbered, reproducible frame-by-frame analysis of the flight 175 image. Using the Fairbanks video, Grossman calculates a zero percent deceleration. In fact, as the plane enters the building, some frames appear to show a slight acceleration.
This is most bizarre and must be either a,
Reality, of course, makes acceleration
impossible. I personally think it is a measurement error from a single
frame, as this acceleration frame comes right after a deceleration frame.
Thus, if this one data point is an error, it implies an offsetting error in
an adjacent frame, given the fixed aggregate time budget.
Eric Salter followed with his own analysis and claimed 13% deceleration based on frame-by-frame study using one of the 2-3 Fairbanks video variants. One of the suspicious facts about the Fairbanks video(s) is that the FBI had possession of them before they went public.
Therefore, Salter artificially slows down his plane trace yet the plane blur goes off ahead and Voila!
Deceleration falsely established...
For my own analysis, I decided to use the widely known Scott Myers camera pictures, so I didn't have to worry about compression issues, frame rates, etc. I found the highest resolution version I could get my hands on in order to minimize loss or measurement precision.
The 15-picture spread was (allegedly) taken using fixed 0.033 second intervals, features a nearly fixed camera angle, and has a fairly decent contrast on key plane features. Thus, it is perfectly suited for frame-by-frame analysis, one of the best videos in terms of high signal-to-noise ratio.
Using unaltered/un-enlarged pictures, a pixels per second average of two pre-impact locations yield a mean of 29 pixels per frame with a standard deviation of 0.6 with a sample size of 6.
The post-impact speeds were calculated in the same manner, but using two different locations on the back tail.
Interestingly enough, the speeds calculated here on the best matching data points show a 29.0 pixels per frame outside the building with a standard deviation of 0.6 and sample size of 6 versus 29.6 inside the building with a standard deviation of 0.5 with a sample size of 5. In other words, I found 4% acceleration.
It is possible, but I was analyzing under 8X magnification. But playing devil's advocate, let's look at a worst-case scenario. Suppose I made a 1-pixel error on EVERY measurement (perhaps I drank too much coffee and was too jittery with the mouse). That would give me an average pre-impact speed of 30 pixels/frame and a post-impact speed of 28.6 pixels/frame.