Anyone else seen this take on 9/11?

[snoopy]

The Pentagon is not the World Trade Center. The WTC is lined with steel beams much tighter than the Pentagon was, "not being a structural engineer" I can't say for sure, but I'd venture a guess that the WTC was built to be stronger than the bomb-resistant Pentagon was

Well, yes and no. The Pentagon has a whole lot more concrete in the outer area than that WTC did. While steel bands are great, how deeply an object will penetrate depends a lot more on simply wall thickness than it does on material. At a given wall thickness, steel will beat the crap out of concrete, and titanuim will beat the crap out of steel. In this case we have very different wall thicknesses, thus it took a lot more power to break through the pentagon wall. Plus, take into account that the pentagon wall was designed to handle an impact, while the WTC walls where designed to support the building. (And still have enough strength to support the building after sustaining an impact.)

[Paul]

How does a plane fly into the WTC and not come out the other side, and yet makes it through 3 rings of the Pentagon each having two walls of steel reinforced concrete?

I have a video on my hard drive that shows the plane crashing right through the second tower (although there wasn't much left intact by the time it came out the other side).

Also, aren't buildings designed to be able to be taken down neatly?

[Topher]

Also, aren't buildings designed to be able to be taken down neatly?

I would have to guess no, buildings are designed to stay up no matter what. Plus, no one has ever destroyed a building as big and tall as the WTC. The WTC would be a different type of demolition too because it isn't supported by a grid of steel girders, it was supported by the network of steel on it's permeter.

[Lothar]

I asked my friend about the Pentagon lawn. She said she went past there taking an airport shuttle about 3 days after the attacks (spent 9/12 in a very empty art museum!) and that the lawn looked pretty messed up. Not like torn out or anything, but like something had scraped along it. The grass was still there but it was in really bad shape.

She also talked about it being totally unreal... that the pictures and TV just don't do justice to how much damage was done to that building. It's actually a very large building, and the collapsed section with all the airplane parts strewn about was a powerful thing to see.

Dedman makes some great points.

[snoopy]

For you physics cats out there, how much energy and momentum does a 2000 pound engine (the core of which is high strength steel) with a diameter of roughly 6 feet have when traveling at 500 mpg? Is it enough to punch through a few levels of the Pentagon?

It's hard to say how deep things will penetrate, because it depends on so many factors once it hits- a whole lot of things can happen. From the numbers you said, it would have about 6.3 KWh of energy (That would run a 400 Watt computer for about 15 hours) To put that into another picture, if the engine stopped in 500 ft (I'm not sure how accurate that figure is, but it's a guess), it would be pushing on the walls of the pentagon with an average of 1.1 million pounds of force and would travel the distance in about 1.4 seconds.

[Dedman]

it would be pushing on the walls of the pentagon with an average of 1.1 million pounds of force and would travel the distance in about 1.4 seconds.

Sounds like that would punch a nice little hole in a few walls heh?

[Ferno]

I asked my friend about the Pentagon lawn. She said she went past there taking an airport shuttle about 3 days after the attacks (spent 9/12 in a very empty art museum!) and that the lawn looked pretty messed up. Not like torn out or anything, but like something had scraped along it. The grass was still there but it was in really bad shape.

So something messed up the lawn AFTER the strike happened?

[Lothar]

I asked my friend about the Pentagon lawn. She said she went past there taking an airport shuttle about 3 days after the attacks (spent 9/12 in a very empty art museum!) and that the lawn looked pretty messed up. Not like torn out or anything, but like something had scraped along it. The grass was still there but it was in really bad shape.

So something messed up the lawn AFTER the strike happened?

Possibly. Or, the lawn was messed up during the crash in a way that doesn't show up well in pictures. It's not like you can tell "the lawn is in great condition, having been freshly cut" in the pictures or anything like that...