How did the WTC Tower fall in 8.4 seconds!?

Question

That means the floors had to pancake 13 floors a second!

Thats like a 13 story building collapsing in ONE SECOND!

Gravity?!! YEAH RIGHT those towers are a quarter mile high..

Answer 1

bombs

Answer 2

There is plenty of commentary (some provided below) by structural engineers and architects on just what happens to a building designed as the WTC was during a prolonged fire, and what is required for implosive collapse (as may be suggested).

I worked in the South Tower for almost two years, on two different floors. The building was an amazing structural feat, but it was built to withstand natural forces of wind and some seismic disruption. The cross-trusses were lightweight and lightly fireproofed. The subfloors were concrete slab, but in my offices, the flooring was really encasement for wiring and other utilities required for workstations. All were highly flammable materials and wouldn't withstand prolonged, intense heat fires. Without the cross trusses, the external beams (on the outside of the building) would bend outwards, causing a vertical collapse (which is what happened).

The two towers fell in different ways, I believe that most of the South Tower's structure above the impact point fell over to the left while the rest of the structure collapsed vertically to the street level. The North Tower, I believe, fell vertically upon its foundation.

Evidence of implosion has not been found. As the 2nd article indicates, preparation for implosion, of a building of this size (these buildings were MASSIVE, few in the world were this large in size and scope) would take a VERY long time, and would include compromising the support structures before an actual detonation sequence (i.e., they'd weaken the vertical support by cutting the steel, over 110 floors, which means the buildings wouldn't be able to support themselves BEFORE the attack if this is what really took place).

13 floors a second is reasonable if you consider that about 30 floors of weight began to pancake down on the first intact floor, which was barely intact as 6-10 floors were compromised structurally due to fire. As the floors collapsed, they gained speed and the collective weight of floors added to the collapse (i.e. the 30 floors would become 43 floors falling in second 2, then 56 floors in second 3, etc, the equivalent of dropping 56 floors of steel and concrete onto the next floor, eventually as the weight increases, the subsequent floors give way much faster).

The intense and broad fire range within the two buildings heated the core beams and the cross trusses to such an extent that the strength of the supporting steel was cut by 50%. That will give way to the 30 or so floors above the impact point, but because the planes came in on an angle and with a majority of the fuel still on board, the fire compromised 6-10 floors in a single impact, rendering the support engineering of the building basically useless.

Without scientific understanding of materials, weight distribution and heat resistance, the implosion conspiracy sounds awfully compelling. But it's just ignorant, stupid and as it's continued, it dishonors the true impact of this event on the lives of survivors and the memory of those lost.

Enough pain has been caused, the perpetrators are known and are being pursued and such ridiculous myths simply make fun of a day and an event that was nothing to laugh about.

Answer 3

Not true. 13 floors a second implies 109 floors, so Ill go with that because I dont know the actual number.

They fall, well say.

Mass accelerates at 1m/s/s; that is, 1 Meter per second, for every second fallen. In lamens terms, for the first second an object falls one meter, on the second it falls 2 meters, and the third it falls 3 meters: So, by Second three, it has fallen 6 meters. By 4 seconds it has hit 4, five is 5, 6 is 6, seven is 7, and eight is 8. So, by eight seconds, matter has accelerated to 36 meters per second.

36 meters is about 108 feet, or over 10 stories. If we assume 109 floors, a story each, than the top of the building would fall 1,090 feet.

So, by the numbers you give, the Towers would drop 10 stories in 8 seconds, leaving 99 stories left.

So, the answer is: Your numbers are wrong.

Answer 4

let's not forget about that gravity pull you toward the center of earth with a force 9.8m/s^2 (meter per second square) and the further away you are from the center of gravity the faster it pulls you in and let's not ignore about weight as well and height. The WTC tragedy involves a lot of physics, mechanics and many other disciplines that would make your head going crazy if you try to understand them all at once, did you know that the way the WTC collapse it was the best and safest way for the surroundings and many people as well, if you want to know more try to go into more details and I will suggest you to ask an engineer (civil and mechanical) and ask them why the upper floors didn't fall instead of the WTC collapsing all...

Answer 5

The 110 story buildings fell at free fall speed. This is an amazing feat taking in that all the steel, concrete, office supplies, parts of the plane, and god sake the bodies cause any resistance to the fall of the buildings.

If you watch very closely to the footage of the towers falling you can see poofs of smoke coming about 20 feet below the floors that are coming down.

If the terrorists hit this building, their plan was for it to FALL, not just to be damaged. (Learning from the 1993 bombing)

Who says that bombs could not have been planted within the building?

Some workers working in the buildings say that within weeks of the attacks the bomb sniffing dogs and WTC/PAPD police were removed from the building as well as parts of the building evacuated for "security reasons".

Any of this sinking in yet, Americans?

Answer 6

it is not true that the WTC pancaked, THE ENTIRE 911 COMMISSION REPORT IS A LIE. it fell in freefall, which would only take 8.4 seconds. so may have been brought down by controlled detonation. but then again how are you going to put explosives in the WTC? maybe they put a few bombs next to the gas pipes which can take out an entire floor, put some on every floor and you can bring an entire tower down.

Answer 7

Well Timmy, the structure inside was failing before you could see the effects on the outside. This is because the Towers had an outer covering called a facade, all completed buildings have them.

Also it did not fall in 8.4 seconds. That is a lie.

Answer 8

Have you ever dropped an apple from a higt, and dropped something that weighs significant;y more? They fall at the same speed. So, technically, the .... wait, I don't know what I'm talking about... MAYBE the 1 story building would take just as long to fall as the towers?

Answer 9

well what 8 seconds of free fall, there is a lot of kinetic energy stored in the weight of the upper portion of that tower. Once it had the momentum the wreckage just plowed through additional floors without being slowed down.

Answer 10

The outer steel structure was weakened due to the high capacity of jet fuel contained on the cross country flights. The jet fuel burned so hot that it melted the insulation off the beams causing them to intern melt and sag. There was a lot of weight and force on those floors. It actually never even reached terminal velocity, so it could have fallen faster had it reached that.

Answer 11

"That's like a 13 story building collapsing in ONE SECOND!"

... or several 13 story buildings collapsing simultaneously as 13 floors each in 8.4 seconds. You may then add in the effect of the acceleration gravity, ( 9.8m/s squared. )http://teacher.nsrl.rochester.edu/phy_labs/Measure_g/Measure_g.html#Heading7

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