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Originally posted by bob2000
Just for the record WTC took around 18 - 20 seconds for the top to hit the ground.
Freefall in a vacuum for the WTC is 9.6468243 seconds (an exact calculation). Its some considerable resistance is if took around 20 seconds to fall.
The big question is was this evident resistance that made it a 20 sec fall due to all air resistance or both air resistance and structural resistance?
Id love to see myself proven wrong though. Show me some quantitative evidence conspiracy theorists, you guys "know" you are right and are "So scientific", this shouldnt be a problem.
bob2000 wrote:
Freefall in a vacuum for the WTC is 9.6468243 seconds (an exact calculation). Its some considerable resistance is if took around 20 seconds to fall.
The big question is was this evident resistance that made it a 20 sec fall due to all air resistance or both air resistance and structural resistance?
The conspiracy theorists are going to want to say its all air resistance. The conspiracy thoerists arent smart enough to verify that though. Theyll need to know the "air resistance parameter" (which they dont have) which is how "thick" the air is, and how the shape of the falling building parts effects its air resistance (shape is a factor too). And assuming they can get this information, theyll have to know how to calculate the fall speed using this information assuming air resistance is the ONLY resistance. Based on all conspiracy sites I have seen, and posts by conspiracy theorists, their is strong evidence that conspiracy theorists cant bring forth any quantitative evidence, all I see is qualitative speculation. Our conspiracy theorists are definitly not mathematics savy. And qualitative evidence just dont cut it.
Id love to see myself proven wrong though. Show me some quantitative evidence conspiracy theorists, you guys "know" you are right and are "So scientific", this shouldnt be a problem.
Originally posted by HowardRoark
Are you counting the time for the top of the building to hit the ground, or the top portion of the building to hit the ground? How can you tell with all of the dust when exactly that was?
Are you sure you aren’t looking at the portions of the building that were falling outside the building envelope?
Those exterior column trees are obviously in free fall, they are also, quite obviously falling faster than the building behind them.
In physics the angular momentum of an object with respect to a reference point is a measure for the extent to which, and the direction in which, the object rotates about the reference point.
In particular, if the body rotates about an axis, then the angular momentum with respect to a point on the axis is related to the mass of the object, the angular velocity and the distance of the mass to the axis.
Without applying torque to the object, with respect to the reference point, the angular momentum is constant. The angular momentum is a measure for the amount of torque that has been applied over time to the object. The object has rotational inertia that resists changes in rotational motion, quantified by the moment of inertia.
Angular momentum is an important concept in both physics and engineering with numerous applications. For example, the kinetic energy stored in a massive rotating object such as a flywheel is proportional to the angular momentum.
Originally posted by MacMerdin
OK...that makes sense except for when people try and use the graphs for the spikes at the beggining of the falls? What would those be if what the graphs are recording is the debris hitting the ground? How could you have a spike in the graphs before the fall if nothing has hit the ground at this point?
1. You say that we'll need to know the "air resistance parameter", when I'm pretty sure you mean the drag coefficient. "Air resistance parameter" sounds like you googled about air resistance and picked the likeliest term for what you wanted to educate us on. Then you say that we don't have the "air resistance parameter", yet are not kind enough in your benevolent wisdom to actually provide it for us. Why don't you help us retards out and tell us exactly what it is? And to at least 10 decimal places, if you will, since we wish to emulate you in your passion for exacting detail.
2. You mention how "thick" the air is as an influencing factor, when I'm fairly sure you mean air density. The only ones who are "thick" around here are, of course, "conspiracy theorists". Some others are just vicious, but definitely not viscous.
3. You also curiously neglected to include in your lesson the fact that air resistance is proportional to the square of the velocity of the object. As the relative speed of an object in the system increases, the air resitance acting on it increases geometrically, which is why objects in motion in atmosphere can reach a terminal velocity. How could a genius like you have missed such a basic and fundamental element? Ahh, I see...you probably didn't mention this because you were trying to test us. Sneaky...
4. You posit that we conspiracy theory half-wits only ever provide qualitative speculation, never presenting any quantitative evidence. However you have neglected to provide any quantitative evidence WHATSOEVER yourself. The single, solitary quantitative statement you made was regarding the results of your free fall calculation for the WTC towers; "an exact calculation" you say. And although I'm probably wrong since I'm one of those birdbrained conspiracy theorists you reference, I'll be brave enough to raise a little pinkie and say...I think you're calculation is wrong.
And the purpose of the point was to show that they have no reason to be "So sure" and "so confident" when their theory's "Evidence" isnt sound and is easily refutable due to how "Soft" it is.
I would say that that is more than enough force to collapse the next floor, building up enough force to shoot smoke out of windows a few floors below.... I think that the above exercise shows that the caps had more than enough energy.
It is not that hard to get quantitive evidence.
It has been asserted that the WTC 1 weighed 200,000 tons. This figure is inferred from a 2002 FEMA report and corroborated by data about other hi-rise buildings built around the 1970s such as the Sears tower and the Hancock building. I want to point out that the government's providing of basic architectural information about the WTC has been piece-meal at best. NIST mentions in a 2005 presentation that the WTC 1 had 100,000 tons of steel. In a 2004 presentation NIST asserts that the 47 core columns had a factor of safety of about 2.25. The 236 perimeter columns had a factor of safety of about 5.0 (it has been asserted that the higher factor of safety for the perimeter columns was to handle wind loads). It has been asserted that the core columns, the main load bearing columns, carried 60% of the building load, and the perimeter columns supported 40% of the building load. This was a big building, like a rock in Lower Manhattan for 30 years.
The factor of safety is based upon the dead load (building materials) of the building and the intended live load (people, office furniture, and similar). The dead load of a floor was 1,818 tons [This is an average, derived from 200,000 tons divided by 110 stories. From Eager's questionable 500,000 ton figure, this is an average of 4545 tons per floor of dead load.]. The floor area was rated 40-150 psf (1.9-7.18 kPa), depending on what the area was going to be used for. Higher load ratings generally were for areas that would support larger than normal loads such as mechanical equipment. Below are floor load estimates based on a review of WTC data contained in a 2005 NIST report. This report contained select scanned images of original WTC specification documents. Because of contradictions in the NIST final report this paper relied on the original WTC specification documents. Data was incomplete so inferences had to be made. The load rating for columns in the perimeter area was 50 psf. The load rating for the core area was up to 100 psf. This comes out to be an estimated 75 psf average for an office floor. The load ratings for floors 110-94 average out to be about 82 psf (3.9 kPa) per floor. On average, a floor's design live load was 1,488 tons. [Note that the live load would not be any different for a heavier building, as the live load is not dependent upon the building materials as the dead load is.] The estimated total weight of a floor, dead load plus live load, is 3,306 tons [Or about 6033 tons according to Eager's assertion.]. Add the factor of safety and the building structure could handle multiple times this load. It is estimated that the average factor of safety for a floor was 3.35 [See below calculation]. This means a floor could handle a total of 11,075 tons before failing [Or, again, according to Eager's figure, 6033 x 3.35 = 20,210 tons to a single floor before failure.]. To visualize, imagine 5,500 2-ton cars stacked in a square about 1/3 of a city block [You'd have to imagine more like 10,105 2-ton cars for Mr. Eager, assuming he's anywhere near close or even addressing a relevant weight. Eager may be included the concrete in the basement for all I know.].
60 * 2.25 = 135
40 * 5 = 200
135 + 200 = 335
335 / 100 = 3.35
The perimeter columns essentially had enough reserve capacity to carry 200% of the WTC 1 design load. The core columns could carry 135%. For floor 97 to collapse, the equivalent of 55% of the core columns and 80% of the perimeter columns would have to fail. That means on average 26 core columns and 189 perimeter columns would have to fail. 75% of the total columns would have to fail. This indicates that the WTC 1 design had lots of redundancy. This was no house of cards.
PE=KE
mgh=(0.5)m(v squared)
mass would [cancel] out
gh=(0.5)(v squared)
(v squared)=2gh
v=SRT(2gh)
v=SRT(2x32ft/(sec squared)X12ft
v=27.7128 ft/sec
Here's a couple of easy equations which you can just plug the numbers into:
d = 0.5 x g x t^2
v = gt
Using metric:
d is distance in meters
g is gravity at 9.8m/s^2
t is time in seconds
v is velocity in m/s
Using Imperial:
d is distance in feet
g is gravity at 32.15ft/s^2
t is time in seconds
v is velocity in ft/s
With a distance of 12ft:
d = 0.5 x g x t^2
=> 12 = 0.5 x 32.15 x t^2
=> t^2 = 12/(0.5 x 32.15)
=> t = SQRT[12/(0.5 x 32.15)]
=> t(ime) = 0.864 seconds for an object to fall 12 feet in vacuum.
v = gt
=> v = 32.15 x 0.864
=> v(elocity) = 27.7776ft/s = 18.939mph
So it takes 0.864 seconds for an object to fall 12 feet in vacuum, and it will be traveling at 27.8ft/s once it reaches that distance.
Originally posted by bob2000
Oh, I see. Your going to attempt to make me look stupid by criticising my terminology. lol. I guess that means your smarter than me becuase you are using correct terminology.
I guess you didnt read between the lines. Its obvious I see conspiracy theoriests as scientifically iliterate. Do you think Im going to use terms like that in my posts? no. Im speaking to laymen, so I have to use laymen terminology so you guys can "get" what Im talking about. I thought the quotes around my terms hinted at that. But I guess not.
Besides, its not the terminolgy that counts, its the number crunching that does. You can use technical terms all you want, and make your self seem like an expert, but it dont mean squat. Its the numbers that matter.
I dont think I really need to provide any quantitative evidence; Im not the one who claims to "know" the truth, nor do I claim Im "so scientific" in coming to my conclusion like you conspiracy theorists do.
As for my figure of 9.6468243 (rounded 7 decimal places) which is different than yours is based on the WTC being 456 meters tall. Ocording to the source I used, it stated that WTC1 was 456 meters tall. But I guess my source was wrong. However, my calculation is correct if that were its true height.
Besides, I stand by my statement that the conspiracy thoerists cant produce quantitative evidence.
Originally posted by bob2000:
[edit on 15-12-2005 by bob2000]
[edit on 15-12-2005 by bob2000]
[edit on 15-12-2005 by bob2000]
[edit on 15-12-2005 by bob2000]
Originally posted by bsbray11
Those numbers are absolutely useless. Great job on figuring them out, though. Real investigative work, there. It's just too bad that you can't do squat with those figures in terms of proving or disproving demolition.
Using an asserted 60/40 steel to concrete ratio, we find that the WTC 1 had 66,667 tons of concrete. Other researches have made estimates upwards to 90,000 tons.