I have to make the explanation concise in a blog and omitt all the pics. Hopefully, the explanation may be a bit more transparent in the Letter.

Here's the deal regarding the CM: Consider a head-on car crash into a solid concrete wall. Before collision, the CM of the car is, say, roughly between the driver and other front passenger. At the end of the collision, the car is shorter. The front end is smashed and the back end more-or-less OK. The heavy motor has been pushed back toward the rear of the car. The CM of the shortened vehicle now resides, say, somewhere below the back seat.

During the duration of the impact, the back end of the car travels a further distance than the front of the car. That is the reason it becomes shorter. Also, during the duration of impact, the center of mass continiously shifts from the front seat to the back seat. So, the front of the car decelerates faster than the back end, and the CM decelerates at a rate somewhere in between.

Same principle with the planes. The front of the plane decelerates faster than the back end. In this case, the very back end of the plane hardly decelerates at all. The CM decelerates slower than the front end, but faster than the back end.

One more concept, momentum: the front end can break up into a bunch of pieces during impact, but by finding the sum of all the little masses times the velocities, you can find the deceleration of the front. The previous paragraph still applies.

I hope this is helping rather than confusing.....

Ningen, I applaud you for considering you might be relying on false assumptions. As I see it, they are encapsulated in this sentence:

how does the plane not slow down as it enters, then suddenly slows down and disintegrates?

Again, I need to stress that it constitutes a gross oversimplification to think of the plane as one rigid body whose behavior could be adequately described by just one or two simple equations. Newtonian mechanics are applicable only to punctual masses, which is why spacious bodies are being handled by their center of mass. This is sufficient to simulate their trajectory under the influence of homogenous force fields such as gravity or the influence of forces easily transferrable to their center of mass, however, it does not suffice to describe complex collisions incorporating lots of deformation. That is what FEA is used for.

The plane's velocity is NOT necessarily equal to that of its tail -- that would only apply if the plane was indestructible, i.e. entirely rigid -- so you simply cannot conclude "the plane does not slow down" according to observations of its tail. Neither can you say "the plane then suddenly slows down and disintegrates" -- there is no plane, there are only a lot of more or less losely interconnected, almost punctual masses we call atoms that, unless their interconnections are somehow compromised, together give the appearance of a plane. Again, these are somewhat approximated within FEA.

Now when one of those atoms, which together happily formed a plane before, is being confronted by another group of atoms which together happily formed a column before, it is determined whether the allegiance to their fellow atoms is greater than that of their opposition. This is mostly decided in old fashioned one-on-ones, as on the battlefields of old, and the last line of the Phalanx doesn't even know what's going on at the frontlines. That last line of the phalanx is the plane's tail...

I sincerely hope this somewhat anthropocentric metaphor helps you to understand why you were basing your argument on overly simplistic misconceptions of matter. Let me know if you catch my drift, please.
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interns < internets

Disinformation is the promotion of misleading arguments. A misleading conclusion is impossible unless it is shown to be supported with misleading arguments. Accusations without credible evidence are just that--accusations.

I don't object to accusations of disinformation if they are supported with very compelling evidence. Does it matter if there is intent involved? No. It's irrelevant if we are primarily concerned with the truth about 9/11. We need to take individuals out of the 9/11 truth debate--just look at the evidence.

About the credibility of the FEMA report: It just happens to corroborate independent studies by Steven Jones. As Hoffman has said: "The "deep mystery" of the melted steel may be yielding its secrets to investigators not beholden to the federal government. Professor Steven Jones has pointed out that the severe corrosion, intragranular melting, and abundance of sulfur are consistent with the theory of thermite arson."

Evidence becomes more credible when it is supported by corroborating evidence. The thermite "hypothesis" is also supported by independent dust sample analysis. Therefore it would appear to be credible. As well, this FEMA analysis of the steel was done by volunteer investigators http://911research.wtc7.net/wtc/evidence/metallurgy/index.html

I am especially inclined to believe that evidence is credible when it is extremely self-incriminating (you don't incriminate yourself--there is no motive) and NIST completely ignored it. What about NIST's credibility? They ignored this study and called it "irrelevant".

It's like the 9/11 commission report: You look at what they say and then see if it's corroborated by other credible evidence. Some things they get right after all...

"but I am concerned that the thermate theory, even if correct, could be "disproved" through release of false samples or a false explanation such as use in cleanup."

Yes, but the fact is that Jones has samples of his own. These can be retested by others.

As soon as NIST admits there was molten steel they are screwed. Many people observed it--even Rudy, mayor of NY. There are photographs of [large pieces of] previously molten steel. Something caused it—and it wasn’t “cleanup” (when they were trying to find survivors) or normal fires.

“We're an empire now, and when we act we create our own reality."