...hitting a stationary mass will lose velocity.

Snerk. If the resistance of the stationary mass is low enough, there will be little or no measurable difference in the velocity of the moving mass. Think of a bullet going through a leaf.

The lower parts of the towers simply could not support the mass that was falling on it, anymore than a straw can support a bowling ball. No explosives are needed to explain the collapse.

Really, the suspect thing here is the measurement of the time of collapse. The towers fell in a mushrooming dust cloud, so what exactly was being measured here?

The resistance to the collapse was in the floor joists. And by joists we mean the bolts which held the floors to the frame of the towers. When the upper stories of the towers collapsed onto the floor below, the floor joists on that floor could not bear the weight of the floors above. The floor was only built to hold its own weight, not ten or twenty floors. Thus the bolts broke and the floors above impacted the floor below.

The next floor was even less able to resist the weight of the floors above. If ten floors collapsed initially, then by the time the 20th floor was reached, there was now twice the weight impacting the joists, meaning the joists could only offer half the resistance of the bolts that originally broke. By the time the 40th floor was reached, the weight was doubled again and thus the resistance was cut in half again. This is a geometric progression.

Did I mention there were 110 floors? Yes, the upper mass did in fact end up slicing through the lower part pretty much just like a bullet through a leaf. Any resistance the joists had was completely overwhelmed by the pancaking of floors. Once the joists were ripped out of the frames, the frames were just sticks of wire and were dragged down with the falling mass. There was nothing that could resist the fall. Any variation from free fall would be minor and hard to detect.

The WTC towers were built lightly compared to the Empire State Building, which is of solid steel and concrete. Steel and concrete can only go so high without collapsing from its own weight, thus the ESB becomes progressively narrower so that it can be as tall as it is. But the WTC towers were just light frames with bolted on floors. This allowed them to reach the heights that they did and to be sheer sided as well. But it also allowed them to collapse in the way that they did, because the only thing really holding up the whole structure together and up was in fact the floor joists. Unlike the ESB, there were no solid columns holding up the building.

A good article explaining all of this in much better detail than I can:

http://vincentdunn.com/wtc.html

Note the part where he says the floors in modern buildings are only designed to hold the weight they are specified to hold. IOW, floors are no longer overdesigned to hold twice their weight as was done in the past. Now if this is true, then ten floors falling on one floor in the WTC towers would have exceeded the capacity of the floor by a factor of ten.

Your other points are just irrelevant and not worth refuting.

Once you understand how the building was constructed, you can understand how it collapsed like that. You can understand how it fell at nearly the speed of free fall. And you can then understand why explosives were not necessary to take the building down and thus why explosives were probably not involved.

Once you understand how the collapse could have occurred, the whole idea of a government conspiracy collapses as well. The government's biggest crime on 9/11 was simply to be caught flat-footed--stuck in the chair for seven minutes, if you will.

The way to figure things out in the reality based world is to figure out one thing at a time. Get one thing figured out, then you have a chance to figure out another thing. That way, things fit together and you don't end up with 200 or more irrelevant points screaming for your undeserved attention. Simpler thought is better thought.

As far as WMD, I decided when we invaded that there were probably no WMD to be found in Iraq. I strongly doubted we would have invaded had there really been a serious threat of WMD against our troops or against our shores. I also knew that the stories of the centrifuge tubes, the Nigerian yellow cake, the drone planes, and so on, were all highly dubious tales and that Colin Powell's presentation to the UN was extremely weak, based on nothing but silly pictures and even sillier audio.

Therefore in my mind I didn't think there would be any WMD found. That's how good thinking works: you put together pieces that fit and then you can come to definite conclusions instead of endless mysteries.