Can someone please cite a natural or man-made small scale real-world example of a progressive collapse?

Question

The term "progressive collapse" seems to have come into vogue after 9/11 as a way of explaining how WTC 1, 2, & 7 collapsed. However, I have yet to see any natural or even man-made small scale examples of this phenomena. Can somebody please provide me with a real world example of a progressive collapse that can be reproduced in a laboratory on a small scale? More precisely, can someone show me how one object can gravitationally move through another object of equal or greater mass at or near free fall speed? Please try to avoid using the collapse of building structures such as WTC 1, 2, & 7 as examples.

Also, please consider the Law of Conservation of Momentum when providing your answer.

Thanks.

Answer 1

Physics lesson: F=MA. Look it up.

While you're looking thinks up, look up L'Ambiance Plaza:
http://engineering.com/Library/ArticlesPage/tabid/85/articleType/ArticleView/articleId/168/LAmbiance-Plazza.aspx

Answer 2

The first thing I thougt of when reading the title of your question was, in fact, the WTC. And I can't think of any other convenient examples of progressive collapse, so I'll have to talk about the WTC. The airplanes hit about a third of the way below the tops of the buildings, and when the fires heated through the fireproofing to bring the vertical posts to red heat, they lost strength and collapsed. (If you have ever watched a farrier adjusting a horseshoe, you will understand this.) The mass of the floors above, amounting to about 150,000 tons, then fell on the next floor below, overloading the posts there just as an enormous hammer blow would. This overloaded the posts on the floor below that, and so on, so that all the lower floors failed. Finally, the upper floors, mostly intact until their bottom hit ground, collapsed from their own momentum. Watch the film carefully, preferably in slow motion, to see all of this at work.

Answer 3

If you have a beam held up by five equally spaced column and one column collapses, the load from this column transfers to the next column. Then this column will become overloaded and collaps. When the Hyatt Regency bridge collapsed it all started with one bolt. That bolts failure passed the loads to the next and the entire bridge collapsed.

Answer 4

The U.S.'s economy, morals, work ethics, leadership integrity, and world credibility!