Yes.

http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm

Go to 6. There is the answer.

Right, so let me know if I lose you, and I will try to make it more clear-

The basic idea is that as the mass collapsed the initial collapsing floors collapsed at a total acceleration less than gravity at STP. At the floors collapsed onto each other their total momentum increased.

Or an easier way to see it,

F= (M+dm)*a = (M+dm)*g_STP-Fimpulse

Here I represented the force downward as an increasing quantity and Fimpulse as the force due to the collision of the total mass at time t-1 to time t. So, as the mass falls it gains more mass, until eventually the total force of the mass falling can be approximated F~(M+dm)g_STP.

Not that more mass falls at a faster rate, rather as more mass falls the effect of the other forces becomes negligible.

This means that for the most part the acceleration can be effectively described by something in freefall, and hence g_STP~a.

Note Fimpulse is a constant as a function of time.
In reply to this comment by Irishman:
I back Choggie's comments.

My own thoughts,
The thermite theory addressed the problem of the freefall speed of the tower's collapse.

There is still no official or third party theory that addresses that problem.

A freefall speed of collapse explicity implies no resistance, and that is impossible for 3 of the buildings that collapsed at freefall speed unless they were demolished.

If someone can explain how the freefall collapses were caused by the fire, then they will have solved the riddle.

This is for the scientist who doesn't know any other scientists who disbelieve the official 9/11 story, here are three of them presenting their case at the American Scholars Symposium.

http://video.google.co.uk/videoplay?docid=-5004704309041471296

This video is also for those of you still out there who think that these buildings were brought down by the aircraft impacts. As for the amount of people involved having to keep it secret, well, the JFK asassination was whitewashed and covered up for all these years. And it's common knowledge that half of Hollywood know that 9/11 was an inside job.

Good to be on board here, I'm an old TAYTV fan! Yay!