For smart math physics people?? 911?

Question

http://video.google.com/videoplay?docid=-4322650841860671469&q=world+trade+7
This vidieo gives a little more detail to my question. I've asked this questions several times. Its directed to the people who call us realist "crazy conspiracy theorist". Take the time and give me a scientific response to show how the World Trade Centers 1&2 and building 7 could have fallen at freefall speeds meeting no resistance. Without it being a controlled demolition. I'm fair I'll give best answer if you can disprove this "theory" beyond a reasonable doubt. Even on the far outside number of 12 seconds would not account for all the resistance of the concrete and steel of the rest of the building. If you disagree prove it. And for supporters add comments if you wish.

This video only measures 100 meter of the collaspe thats why they get 4.5 seconds. The 911 commision report's "official"number is 10 secs" Thats only 1 sec short of fall in a vacume 9.2 seconds

NOPE ........no answers yet. Checked out that link .........Nope no explanation there

Shock wave?? NOPE..... even if the floors were damaged below from a "shockwave" would not account for the whole floor starting to fall before the impact of the floors above. The "shockwave" would have hardly been sufficient to dislodge all the floors to prevent ANY resistance.

The collaspe did not start when the plane hit the building. In CNN video of the towers you can plainly see debri shooting out horizintally. Steel has a tendancy to bend before it -shatters into pieces?? The buildings were designed to take the impact of a 707, which buy the way had more fuel capacity that a 767.

The impact did not cause the buildings to fall they stood for about an hour before they fell. Even the official report credits the buildings collaspe to intense heat weakining the steel which is also bull. Jet fuel does not reach the 2000 degrees the steel was certified to take for hours by UL laboratories. NEXT

Yes it would take a building of that crosection awhile to reach terminal velocity. And dont you mean 9.8 FEET per second squared?? professional .....what??

The fact that the ball moved at a constant and did not allow for the time to reach termonal velocity doesn't that help my theory. If they didn't use a high coeficient for friction the building would have beaten the ball to the ground much faster. I only have a high school education this is not rocket science people. Come on!!

also ....... The second plane almost missed it did not center the building missing the core. So the damage to the buildings was not consistant yet the collapse was??

ok it was meters but???

However, since A has twice the mass of B, it resists accelerating twice as much as B. These two effects - A has twice the force, but it resists twice as much - cancel each other out, and A has the same acceleration as B in free fall!

If A and B both start falling from rest, and they both have the same acceleration (g = 9.8 m/s2) then they will have equal velocities as they fall, and they will both hit the ground at the same time.

Answer 1

I am not surprised by the "analysis" of some of the people here. sometimes despite your practice of science, you only arrive at conclusions you want to arrive at and many of the people who are trying to "analyze" your problem are afflicted by the same desire to have their analysis match the results they want to see.

The buildings did take somewhere around 10-15 seconds to collapse. We don't know exactly how long but its in that vicinity. Let's do one simple calculation:
The WTC's were about 1368 feet tall, and had 110 floors. So each floor was about 12.4 feet tall. We will assume that the pancaking theory is correct and each floor collapsed when the floor above it collapsed on top of it. Also assume there was no time lost in the actual failure of the structure, and the failure was instantaneous.

Now if the pancaking theory is correct then, in a hypothetical case, floor 109 can't start falling until floor 110 hits it. After it does hit 109, both 110 and 109 start falling and hit 108, as soon as that happens 108 fails and 110, 109, 108 starts falling. This is the usual theory of progressive collapse. The floors below the collapse zone can't collapse ahead of time because that would mean action at a distance. So if you develop this model it would look like a relay race, where each floor is at rest till the floors above it reach it, at which point the undamaged floor starts moving as well. This implies that each floor starts from rest and falls through 12.4 ft before the floor below it starts to fall. 110th floor falls through 12.4 ft, hits 109th floor. 110 and 109 start falling together for 12.4 ft, hit 108th floor. 110, 109, 108 all start falling together for another 12.4 ft etc etc..
So at no point of time the floors could have accelerated for more than 12.4 ft. Use equation: s = 0.5.g.t^2

this gives you the time to fall 12.4 ft as 0.88 secs. So basically it is a cascade of 0.88 second falls of one floor to the next, ASSUMING no time was lost in the actual structural failure. For 110 floors this would mean 110 * 0.88 seconds = 96.8 seconds.
So for the buildings to have collapsed from the top it should have taken about 97 seconds. Now the planes didn't hit at the top, they hit near the 90th floor I guess? So you can take off the first 10 floors and consider them as being one single block falling together. The time taken then should be 90*0.88 = 79.2 seconds.

As someone else said that there is possibly a 20% error in the measurement of the time for collapse. Taking that into account and correcting the measured time of 10-15 seconds we should be looking at a time of 12-18 seconds for the collapse. However as you see the time we arrive at by using equations of motion is not anywhere close to 12-18 seconds. It is at least bigger by a multiple of 5 and at most by a multiple of 7.

That is an error of measurement of 500% to 700%. I dare any of you to prove that such a huge error is merely due to observation only.

Instead of 1 floor collapsing at a time, if you assume that 5 floors collapsed en bloc at a time then the total time to collapse from the top (110th floor) would be 61.2 seconds. Again if you take the collapse to have started from the 90th floor then this time becomes 50.1 seconds. (I will presume that those answering here can work out these numbers following the same model used in the previous paragraph.)
Anyways, so even with a progressive collapse of 5 floors at a time the calculated value would be at least 280% to most 417% off the 12-18 second value.

Again, I dare you to prove such a huge difference due to error in observation only.

Building 7 is a no-brainer. Undoubtedly free fall. Actually if you look at the video footage you can see quibs of smoke coming out of the windows of this building AND the quibs move sequentially upward. If anyone wants to say that those were caused by the pressure of floors pushing out air from the windows, then I am sure they can explain why the quibs were in an upward sequence.

Prof Steven Jones of BYU Physics department has a paper. If you want a thorough repudiation of the official conspiracy theory you should read his paper:
http://www.physics.byu.edu/research/energy/htm7.html

This post is getting too long so I will not try to address any other scientific anomalies. I hope this satisfies the asker and provokes the other answerers to think about the problem again, with an open mind. Science works best when you do not have a premeditated solution that you want to arrive at.

Answer 2

Many responders have missed an important point: the buildings did not collapse when the airplanes hit them, but sometime later (~1.5 hours - which was a good thing because it let people below the fires get out) when the fires had weakened the structures to the point that they could no longer withstand gravity and collapse. The steel posts were surrounded by fire retardant, but the retardant was not up to the task of containing a fire fueled by several thousand gallons of JP-4.

Looking at the pictures of the collapse, we see that each floor remained intact until the impact load of the floors above it crashing into it overwhelmed the strength of the supports.

All in all, I see the question as a totally pathetic attempt to deny reality in order to attempt to excuse the inexcusable. And frankly, I find it utterly disgusting.

Answer 3

The issue does not seem to be that the buildings collapsed at the speed and profile they did. Issue seems to be could the buildings done so under the conditions that were observed - two aircraft rammed into the two towers at the upper floors of each tower. Or could this have occured only through controlled demolition. The "theory" assumes or asserts the following:

1) That a controlled detonation could indeed create the collapse profile observed.

2) That for a collapse to occur at near free fall rate in a vacuum an actual vacuum must be created - supposedly by implosion from detonation.

3) The fact that the building fell within their respective foot prints indicates controlled detonation - supposedly because that is the objective of controlled detonations.

Assertion (1) indicates that the theory accepts all of the physics observed including the way floors collapsed, speed of the free fall, and the movement and final accumulation of debris after collapse. What is asserted that this profile could only occurr by design rather than the conditions actually observed 911.

The fact that the 2 towers collapsed with nearly the same profile indicates that the similarity of the structures was the primary determinant of the collapse profile. One would then have to show that the observed conditions could not duplicate the same conditions as a controlled or designed collapse. For this, the theory presents next two assertions to support their point.

Assertion (2) - the fact the towers fell near the speed expected by a "ball" in free fall in a vacuum indicates that air resistance or bouncy of the upper tower floors was not relevant. As the mass began to move it quickly obtained kinetic energy from gravity that apparently overwhelmed the ability of the structure of the lower floors to resist the energy. Hence even the buildings structure was not much resistance. The fact that one floor could not resist the initial fall might be astonishing (the 1st second) - the fact that remaining 70 or 80 floors would collapse by the same mechanism is not so surprising. The reported "detonations" would be inconsistent with sequence detonations at each floor to control collapse.

(The calculation of the difference between free fall and actual fall performed by Professional Student is sufficient to demolish this assertion. Imagine that - an entire theory demolished by a simple computation. Well done. But since the theory accepts that designed demolition could create the same result - the remaining assertion should be addressed to leave no doubt.)

Assertion (3) the debris within the buildings foot print only indicates that practically all the energy was focused vertically downward rather than outward radially or lateral motions to one side. The video shows that indeed the top floors moved vertically downward across the entire structure. Once this motion was established there would be very little that could change it. One might argue that lower floors through non uniform resistance could change the motion - but as is already shown - the resistance of the floors was not a factor. All energy was directed downward - something that controlled detonations depend upon. If fact - they attempt to move the center of the structure down first to pull the corners inward - something not observed in the video.

The simplest explanation is that all support on the effected floors gave out at the same time. Initial motions must have insured that this occurred within the initial second of motion. It might be astonishing that this would occur in the initial moments, but once it occurred simple physics would take over to explain the rest. The fact that it occurred twice would indicate more systematic factors common to both towers than a conspiracy. At least - all explanations would have to be exhausted before intelligent design could be considered.


In fact I would assert that before 911 that there was no experience or understanding of how to actually bring the towers down in a controlled collapse. The physics that was surprising in the towers coming down would be unknown to anyone attempting to bring the towers down like a Las Vegas Casino. I think there should be investigations to understand how it occurred but I would surprised that someone could understand it before it actually happened.

Thanks for problem - I was wondering what all the hub bub was about. Apparently - another version of intelligent design.

(The placement of the airplane's initial impact is irrelevant to the final result. The actual collapse occurred substantially later and sufficent time had lapsed to establish near identical conditions throughout the floor(s) where they impacted. All indications are that building's structure dominates over all other factors in characterizing the collapse. In other words, what failed, failed in both towers because the conditions where near the same. To build a case for this theory - one would have to show conditions where substantially different to warrant different results.)

Answer 4

WTC1 and WTC2 fell as a result of being hit by large airplanes at high velocities, and the fires that resulted. It has been mentioned that these buildings were designed to be able to withstand an airplane crash, however consider the fact that E = mv^2. The planes that hit the WTC buildings were flying faster than a similar plane would be expected to fly. If the buildings were designed to withstand a crash at approach speeds, then it is likely that the planes hit twice as fast as the designers designed for. Because energy scales quadratically with speed, that would mean the buildings were hit with 4 times more energy than would be expected from an ordinary crash.

You mention that the first 100m of the fall takes 4.5s and that is evidence of the building falling at free fall speeds. At free fall an object fall 9.8m/s^2. So over 4.5s we should expect something in free fall to fall 198.45m. If the building fell only 100m in 4.5s then that is evidence the building met considerable resistance.

The video used is deceiving, they set the coefficient of friction to be very high, and the ball falls at a constant speed. This only happens when an object reaches terminal velocity. An object with the density and cross-section of a building would take a long time to reach terminal velocity.

In your comment you assert that the rate of fall is 9.8ft/s^2 rather than 9.8m/s^2
Please see the following web pages.

http://en.wikipedia.org/wiki/Gravity_(Earth)
if you think that web page is inaccurate, please see:
http://www.aerospaceweb.org/question/astronomy/q0227.shtml
or:
http://www.school-for-champions.com/science/gravity.htm

You also assert that the second plane nearly missed the building. That may be true, however that will make little impact on the center of mass of the building, and both buildings fell not surprisingly to their center of mass.

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Your most recent comment about object A and B both falling at 9.8m/s^2 is correct as far as I can tell. You are also correct that a more massive object will resist acceleration more than a less massive object. I'm not sure what you are getting at though.


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Someone in another form pointed out that I had forgotten the 1/2 term in calculating the distance to fall. So I did my calculations incorrectly. It appears that if the building did fall 100m in 4.5 seconds that is very close to what we would expect to see in free fall. Interesting.

Answer 5

The vibrations from the collapse of WTC 1&2 destabilized the foundation and skeleton of 7. It became more unstable and the vibrations pushed inward on the skeleton. As each floor fell it aided gravity in speeding up the collapse by providing a more forceful push on the lower floor than gravity by itself.

Answer 6

Basic stupidity...

The physical principals of a "controlled demolition" are those of a caused "structural fault".

In controlled demolitions all you are doing is finding a structural fault and utilizing it to bring down a building.

In the events at the World Trade center a structural fault brought down a building.

After reviewing your "evidence" I saw nothing out of the ordinary for catastrophic support failure on a multistory structure with limited internal support.

Answer 7

the shockwave in a solid travels much faster than in a gas

this means that as a building collapses the percussive shock will destroy lower floors even before the upper ones reach them

of course, the upper floors cannot fall faster than they would in what you call free fall, but they will meet little if any resistance

Answer 8

When a building is collapsing, it is effected by not just the pull of gravity but the momentum of the building pushing it downwards. Momentum is defined by mass*velocity, so the building would be given an extra "push" on its way down.

Answer 9

Theres no way a crappy amateur video like this can be used to measure anything with less than 20% error in either distance OR time. The computer generated graphs are nothing more than computer generated graphs designed to twist the minds of people who had no formal pre-comuter training in geometry or dynamics.

What a pile of rubish..........

Answer 10

my 2cents worth to get me to level 2...
i think this has been answered by the above, but i add
would something fall faster if there was a low pressure below it and a higher pressure above it than if it were just in a complete vacuum?