The Laws of Physics

[canetoad]

Tower 1 was hit & damaged between floors 92-98, leaving 12 floors above the damage zone.

Tower 2 was hit & damaged between floors 78-84, leaving 26 floors above the damage zone.

Why are the collapses so similar? The cores were oppositely oriented, the kinetic energy from above was, in tower 1, less than half that of tower 2.

Can anyone come up with an irrefutable reason why the collapse time for both towers was nearly the same when the damage was quite different.

[Make7]

1. How did you determine that the collapse times were nearly the same? ( nt )

[DoYouEverWonder]

12. Wow, a whole 2 seconds difference between the two collapses

NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A).

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

BTW: Both Towers fell faster then WTC7. WTC7 was a classic CD. WTC 1 & 2 were not.

[greyl]

13. "times for the first exterior panels to strike the ground" nt

[DoYouEverWonder]

15. Here's the original question from the report

6. How could the WTC towers collapse in only 11 seconds (WTC 1) and 9 seconds (WTC 2)—speeds that approximate that of a ball dropped from similar height in a vacuum (with no air resistance)?

It appears they are answering the question, but slipping that little tidbit in about the first panels to hit the ground makes a big difference. Upon more careful reading of their statement, they never do answer the question has to what the total collapse times were.

[vincent_vega_lives]

24. Look at the pics

Is there debris below the colapse point? If so then it wasn't free fall.





ooops. The debris is well below the level of collapse.

[DoYouEverWonder]

41. Well you better let the folks at NIST know that they didn't

because they seem to think otherwise.

NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A).

As documented in Section 6.14.4 of NIST NCSTAR 1, these collapse times show that:

“… the structure below the level of collapse initiation offered minimal resistance to the falling building mass at and above the impact zone. The potential energy released by the downward movement of the large building mass far exceeded the capacity of the intact structure below to absorb that energy through energy of deformation.

Since the stories below the level of collapse initiation provided little resistance to the tremendous energy released by the falling building mass, the building section above came down essentially in free fall, as seen in videos. As the stories below sequentially failed, the falling mass increased, further increasing the demand on the floors below, which were unable to arrest the moving mass.”

In other words, the momentum (which equals mass times velocity) of the 12 to 28 stories (WTC 1 and WTC 2, respectively) falling on the supporting structure below (which was designed to support only the static weight of the floors above and not any dynamic effects due to the downward momentum) so greatly exceeded the strength capacity of the structure below that it (the structure below) was unable to stop or even to slow the falling mass. The downward momentum felt by each successive lower floor was even larger due to the increasing mass.

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

[vincent_vega_lives]

42. I don't disagree with that statment

"little resistance" "essentially in free fall" is not "No resistance" and "At free fall" which is constantly touted as the proof that the building was demolished with explosives.

[DoYouEverWonder]

43. You can run rings around yourself logically

all day for all I care. But give it up, you aren't proving anything.

[vincent_vega_lives]

44. Its pretty simple really

It proves the building didn't collapse at free fall speeds, for what its worth.

[tenseconds]

45. How

How could it be going faster than free fall and it is. Explain that.

[canetoad]

16. That small a difference?

Lots of figures floating around, thought I still reckon it's a big red herring to be quibbling about a second or two in the general scheme of things.

So if NIST says the collapse times were 9 and 11 seconds, the collapse-per-floor times would be 0.1 second versus .08 second. So would a physicist expect a difference of .02 of a second in the collapse, if the weight above was more than double?

Thanks for posting the NIST figures.

[greyl]

2. They're cool.

Can anyone come up with an irrefutable reason why the collapse time for both towers was nearly the same when the damage was quite different.

Firstly, I note that you say the collapse times were "nearly the same". That means they were different. That makes your question moot.

Answering it anyway, it's because of the similarity of construction. After the collapse was initiated, the laws of physics dictated that the buildings would be subject to very similar forces.

[canetoad]

3. I said irrefutable chaps. Next............

[greyl]

4. Like Yosemite Sam wears? nt edit:

I see you have yet to refute my reply, nor have you responded to Make7 with some solid figures to work with.

[canetoad]

6. You ignored

Several questions that I think are pretty valid and skipped to the last line and homed in on the word 'nearly'. That's a bit selective kiddos.

So come on, gimme your take on this.

[greyl]

7. Bullshit.

You asked a total of one(1) question phrased in two ways, and I answered it after noting that your question includes the answer you're looking for.

canetoad: Why are the collapses so similar?

canetoad: Can anyone come up with an irrefutable reason why the collapse time for both towers was nearly the same when the damage was quite different.

greyl: Firstly, I note that you say the collapse times were "nearly the same". That means they were different. That makes your question moot.
Answering it anyway, it's because of the similarity of construction. After the collapse was initiated, the laws of physics dictated that the buildings would be subject to very similar forces.

Make7 and I have asked you questions that you haven't answered.
Why did you bother to start this thread?

[canetoad]

8. Not for your education, for sure

Why so snippy. Just answer the question.

[greyl]

9. You can't be serious. I gave an answer.

You haven't even tried to refute it.

[canetoad]

10. Very fukken serious mate

You are talking in circles.

[greyl]

11. Please see post #1. nt

[canetoad]

14. No play anymore.

Until Greyl grow up.

[Nozebro]

22. It's the common language of OCT'ers (Official Circle Talkers)

What else would you expect from someone trying to "defend" (whether out of personal belief or _____) the indefensible?

[tenseconds]

56. figures

Lets see your "solid figures" on the amount of resistance from the lower section.

[MervinFerd]

19. Why must the conventional (correct) explanation be "irrefutable", but

the ConspiraToon explanation be "not disproven beyond any possible doubt"??

Seems unfair somehow.

[mirandapriestly]

51. what makes the conventional correct?

You must have a real thing for authority.

[cherokeeprogressive]

53. Irrefutable Chaps

I own a 2006 Harley Davidson "Road King". It's my FOURTH Harley.

I've never heard of "Irrefutable Chaps".

Next?

Chaps are for pussies. Responsible riders who are concerned for their own safety don't bother with CHAPS, they wouldn't help you in a pinch anyway.

Next?

[Name removed]

5. Deleted message

Message removed by moderator. Click here to review the message board rules.

[Nozebro]

23. Don't hold your breath. It's not going to happen. OCT'ers won't do it.

"Stop playing little word games and give us some reasonable, rational, MANLY responses here."

[tenseconds]

55. no free fall

And the laws of physics dictate that the speed of the mass falling would be resisted by the lower structure.No free fall without explosives.

[Anarcho-Socialist]

17. Why don't you ask some structural engineers?

You could do your own research by asking someone with expert knowledge in that area, unless such a person is found on DU.

[MervinFerd]

18. Talk to actual experts? People who actually know the field? WOW!!!

What a concept!

But, you're likely to get a mundane answer, like "The towers fell because they were hit by jetliners filled with fuel."

-LOTS- more fun to go off and find some random particle physicist from Utah who has eccentric opinions.

[savemefromdumbya]

20. tower hit second 'fell' first

yes they were both blown - demolition would cause the time similarity. Look at the seismograph charts. I bookmaked them and now I can't find them.

[greyl]

21. First tower to fall was hit at a higher speed, study finds.

Researchers trying to explain why World Trade Center's south tower fell first, though struck second, focus on new calculations showing passenger jet that hit south tower was flying much faster than other hijacked plane; speed of two planes at impact has been painstakingly estimated using mix of video, radar and even recorded sounds of planes passing overhead; two sets of estimates, by government and private scientists, show that United Airlines plane, which struck south tower, was moving so fast that it was at risk of breaking up in midair as it made final turn toward tower; in addition to speed of planes, other factors causing south tower to fall first include combination of structural damage and fires; south tower was also hit at lower point, meaning there was more weight bearing down on damaged floors; difference in towers' survival times translated into difference in amount of time tenants and rescue personnel had to get out; south tower fell within 56 minutes and north tower fell after 102 minutes

http://select.nytimes.com/gst/abstract.html?res=F50E11FF3A5A0C708EDDAB0894DA404482

[Ezlivin]

25. "[W]as moving so fast that it was at risk of breaking up in midair"

The plane was flown beyond its limits.

On Boeing jets, the pilot can override onboard computers and their built-in soft limits.

"It's not a lack of trust in technology," said John Cashman, director of flight-crew operations for Boeing. "We certainly don't have the feeling that we do not want to rely on technology. But the pilot in control of the aircraft should have the ultimate authority." Source

That just means that the hijackers are that much more qualified.

Pretty soon these hijackers will be believed to have been the most skilled pilots ever known.

How can we ever hope to defeat such a resourceful and intelligent enemy? Particularly when they can so skillfully exploit our own technology against us....

[greyl]

26. The plane wasn't flown beyond its limits, obviously.

"it was at risk of breaking up in midair"
But, it didn't.

How you can say that this proves the pilot was super-skilled is beyond me.

[OldSiouxWarrior]

27. No, you have that backwards.

It takes a skilled pilot to always keep a plane within it's flight parameters. That's what a lot of flight school is about. Any idiot at the controls can make the plane go outside it's designed envelope. In this case, it appears that flight 175 had the throttles rammed all the way on, past the maximum safe fuel amount for that altitude.

Think of it like this. Any idiot in a car can redline the engine, but it takes a skilled driver to keep the rpm just under the redline.

[greyl]

28. Plus, I think he's talking about Flight 77, not

the ones that hit the towers.

[Ezlivin]

31. I took it from his quote

...two sets of estimates, by government and private scientists, show that United Airlines plane, which struck south tower, was moving so fast that it was at risk of breaking up in midair as it made final turn toward tower

[greyl]

33. Ah, my quote? D'oh! nt

[tenseconds]

46. No.

No. He's talking about 175.

[Ezlivin]

30. You overlooked something

If the pilot wanted to take the aircraft to the verge of breaking he would have to override onboard computers and their built-in soft limits.

So the pilot would have to know to do this (how much of this overriding they teach in flight schools is unknown to me, as I am only licensed in single-engine general aviation aircraft) and then would have to do it. In turn, that meant that they knew the approach path and/or method they used would take the aircraft beyond its normal operating parameters.

We have two schools of thought about the pilots:

1. The pilots were skilled
2. The pilots were unskilled

If they were skilled, then all of the aforementioned adjustments and overrides are quite plausible.

If they were unskilled, then they had an extraordinary amount of luck that day. But 9/11 was a day filled with coincidences and oddities.

[greyl]

34. They were somewhat skilled and chance explains the rest.

As far as I know, all of the hijackers had at least 250 hours of simulator training and they all had commercial licenses. I don't think they hit targets the size of a dime. Plus, don't forget that we know that ¼ of their missions failed that day.

[tenseconds]

57. Hani Hanjour

Hani Hanjour couldn't fly his way out of Cheney's pacemaker.

[OldSiouxWarrior]

36. See post # 32

According to him the 9-11 planes didn't have that computer system.

[Goldilocks]

48. The jets obviously hit the towers, hence it is equally obvious the

pilots in those planes were skilled enough to guide their jets to hit the towers.

[tenseconds]

58. jets

The jets were identified? No court evidence there. Sorry.

[Make7]

32. That article was not reporting on 767's or 757's.

Edited to change post title - I used the title from the article originally

Unlike Airbus, Boeing lets aviator override fly-by-wire technology

Monday, March 20, 2000

By JAMES WALLACE
SEATTLE POST-INTELLIGENCER REPORTER

    <- snip ->

Should pilots or a computer have the ultimate control authority over a commercial jetliner as the plane approaches its design limits in an emergency?

    <- snip ->

Dramatic advancements in technology have made it possible for planes built by either manufacturer to be flown by computers from shortly after takeoff through the landing.

But Airbus has taken a much different philosophical approach to using computers than its rival. The European airplane maker designed its new fly-by-wire jets such as the A320 with built-in hard limits, or "protections."

The Boeing Co., on the other hand, believes pilots should have the ultimate say. On Boeing jets, the pilot can override onboard computers and their built-in soft limits.

"It's not a lack of trust in technology," said John Cashman, director of flight-crew operations for Boeing. "We certainly don't have the feeling that we do not want to rely on technology. But the pilot in control of the aircraft should have the ultimate authority."

    <- snip ->

The only Boeing plane with fly-by-wire technology is the 777.

Cashman, who was chief pilot for the 777 program, said Boeing could have designed the 777 with the same hard limits as those in the Airbus planes.

"They could have been absolutely identical, but we chose to go a different path," he said. "It was based on what our customers wanted, and what we believed was the safest way to operate jet transports."

http://seattlepi.nwsource.com/business/boe202.shtml

The article wasn't even reporting anything related to 767's or 757's.

- Make7

[mhatrw]

35. So they can estimate the planes' speeds, but they can't tell

when they impacted the towers.

[greyl]

37. The more accurate our measurement of speed,

the less accurate our measurement of place. It's all in the quantum physics handbook, which has no bearing whatsoever in this case.

[Make7]

38. LOL! ( n/t )

[savemefromdumbya]

39. That is actually wrong

[greyl]

40. Actually provide an argument. nt

[leftofthedial]

29. because that's the way jesus wanted it

and if you persist in spouting tin-foil facts that have an anti-OCT bias, the terrorists win.

[mirandapriestly]

52. That IS the prevailing mentality, isn't it? eom

[LARED]

47. irrefutable

The towers were the same height, so they fell at nearly the same speed.

Hey, this physics thing is easy. I think I'll build a particle accelerator this afternoon.

[mirandapriestly]

49. I think something went wrong with the plan

There is a reason for the car bombs and blowing up wtc7 , also the planners must have known it made no sense for the buildings to fall with basically no "injury" to the lower 3/4ths of the buildings (almost no damage to 7). I think something else was supposed to happen. There were the reports of another plane, that could have been destined for 7 and perhaps it was supposed to strike part of it and hit the lower halves of the towers, something like that.

[mirandapriestly]

50. Tell me why a few seconds makes a difference

and canetoad is asking the question, not you. What a nasty post.

[Nozebro]

59. They aren't very good at ANSWERING anything and when they do, you

can be sure it will be void of substance, loaded with invective, and probably responsive to some minor detail that doesn't have much, if anything, to do with the question asked.

I note you mentioned a "nasty post" from one of them. That's what I'm talking about. Sometimes it almost seems as though they have a Guardian angel, like Reagan's Teflon.

[Make7]

54. RE: The Laws of Physics

• Tower 1: collapsed 1 hour and 42 minutes after the plane impact into its North wall
  
• Tower 2: collapsed 56 minutes after the plane impact into its South wall
  
• (Tower 1 remained standing 82% longer)
  
  
• Tower 1: top section tilted about 8 degrees to the South at the beginning of the collapse
  
• Tower 2: top section tilted at least 20 to 25 degrees to the East during the collapse
  
• (Tower 1 tilted about 60% less)
  
  
• Tower 1: collapse time was approximately 16 seconds
  
• Tower 2: collapse time was approximately 12.7 seconds
  
• (Tower 1 fell at about 63% the rate of Tower 2, using the full height of each tower)

Perhaps you could explain in more detail what you mean when you say that the collapses are so similar.

Could you also provide the collapse times upon which you are basing your premise that they were nearly the same?

- Make7