most people don't see a problem with a building collapsing like a house of cards into it's own footprint. i've even heard people say "well, aren't they suppose to do that so they don't fall over and destroy buildings around it?"
can you imagine working in a building knowing that the engineers didn't design it for your safety but rather the safety of building surrounding it!
most people don't realize how hard it is to "pull" a building even when done by experts who spents weeks carefully planning it.
here's the fottage of WTC 7 coming down from exterior and minor fire damage:
https://youtube.com/watch?v=LD06SAf0p9A
if the floors that caught on fire collapsed, wehy would the entire building collapse? they wouldn't, the floors would pancake each other and stop. now here's what happens when a demo job fails. as you can clearly see the building stops collapsing because the explosives failed.
https://youtube.com/watch?v=rIEBLdd6W3Q
https://youtube.com/watch?v=UsePU...eature=related
now why wouldn't these buildings keep going right into the ground once the momentum has started?