Why did the collapse of WTC take only 9.5 seconds?

Question

An object no matter the mass is which fall from the same height will take the same time to reach the ground (Galileo's Pisa Experiment).

If the height of WTC is 526.3 meters and the gravity constant is 9.8 m/s^2 then the time needed by the roof top to reach the ground is given by:

h=1/2*g*t^2
t=sqrt(2*h/g)
=sqrt(2*526.3/9.8)
=sqrt(107.4081633)
=10.36379097 second

but why in the video recording it took only 9.5 seconds. It is so odd isn't it?

#Both of the towers burned for a lot longer than 9 seconds!

I meant the top floor reached the ground by only 9.5 seconds. I did not say the burning process, I said the duration the fall take, as a point of reference we can take the position of the roof top.

#(By the way, your measurements don't take into account that the towers collapsed from the middle, not from the bottom. Suspiciously, the collapse began precisely where the planes hit, not from the bottom as they would have if they had been demolished by explosives.

No, look here: Why do everything falls to earth? Because the earth has gravity force, the force is 9.8 m/s^2. This is a simple senior high physics question: if there is no external force, then a solid structure, no matter the mass, will fall with the speed and duration given by the Newton's Laws. So the top of WTC is 523.6 meters above the ground.

It cannot reach the ground faster than 10.36 seconds as I calculated. Except there is an external force from the foundat

#So you are trying to say that Bush and the CIA changed the laws of physics in order to frame Osama? Wow, Bush is God now.

No, I'm just curious really... No one need to be God or breaking the laws of mechanics to perform that phenomenon. We only need an external force from the foundation of the building to speed up the collapse process.

#There is somekind of compression process in the materials so that the force from the top accumulate so the process can be faster than your simple prediction.

I don't know for sure, but if you got an A+ in 10th or 11th grade physics, you should know that gravity is a conservative equation. It means if you fall you cannot speed up your falling time. If a building collapse, nothing can increase the force of gravity so that the falling time faster. The properties of conservative fields are given in college Vector Calculus, you should read Kreyszig's books, Purcell-Varberg books, or other related topics

The only way can is an external force. In the case your falling from building, the only way to speed up the time you reach the ground is: you need an external force from the ground (someone pulling you)

#There is somekind of compression process in the materials so that the force from the top accumulate so the process can be faster than your simple prediction.

I don't know for sure, but if you got an A+ in 10th or 11th grade physics, you should know that gravity is a conservative equation. It means if you fall you cannot speed up your falling time. If a building collapse, nothing can increase the force of gravity so that the falling time faster. The properties of conservative fields are given in college Vector Calculus, you should read Kreyszig's books, Purcell-Varberg books, or other related topics.

The only way can is an external force. In the case your falling from building, the only way to speed up the time you reach the ground is: you need an external force from the ground (someone pulling you).

#A force at the "foundation" would produce the same free fall speed for the WTC as a force at the top. Gravity is gravity.

Simple if you're falling you are pulled by the earth with 9.8 m/s^2 force. The way to modify this conditions: 1. A positive magnitude force applied to you (someone pulls you up or you bring a chute so that the wind gives you a postive magnitude force) 2. A negative magnitude force applied to you (somone pulls you down with a rope or the wind blows you down.

Why only an external force from the ground: Because the ground is the only thing that doesn't move. If you're playing chute with your friend, there's no way you can pull her/him because you are affected by a conservative force (in this case gravity) too.

#try dropping a piece of paper and a hammer and see which hits the ground first.

I said a rigid object OK! A piece of paper has aerodynamics properties... If you want to try: try to drop a thin book and a hammer together and see which one reach the ground first OK.

The Newton Laws apply in all conditions

Answer 1

911 was an Inside Job.

However, most Americans are not mentally ready to even consider that possibility. People kill other people all the time in order to get what they want... but for some reason, Americans find it impossible that people in governments would kill other people to get what they want.

Trying to use physics probably won't work, since it is too technical. You'll have to use other evidence that is less technical & more easily understandable. For example, if the jets really did incinerate & vaporize along with the hijackers' bodies, how come Mohammed Atta's passport was found at Ground Zero UNSCORCHED?

How come one of the decorated heroes of 911, William Rodriguez, the WTC janitor who was one of the last ones out of the WTC because he was helping the firefighters open all the stairwell doors (he was the only one left with the master key because the other 4 who had the master keys had fled), who was in the basement when the plane hit his building, reported a big explosion in the BASEMENT, just BEFORE the plane hit, and another explosion just AFTER.... and 15 other workers down in the basement back up his testimony? This is in addition to all the other explosions that firefighters had reported after the attack. Of course, all testimony about explosions were stricken from the 911 investigation final report.

All those who have the courage to listen to a hero, watch Mr. Rodriguez tell his story here:
http://video.google.com/videoplay?docid=4380137365762802294&q=william+rodriguez&hl=en

Keep up the work of speaking the Truth!

Answer 2

why do all the conspiracy nuts try to explain this with High school physics when they failed the class in the first place. That law of gravity, "An object no matter the mass is which fall from the same height will take the same time to reach the ground" only works in a vacuum. try dropping a piece of paper and a hammer and see which hits the ground first.

Answer 3

Both of the towers burned for a lot longer than 9 seconds!

(By the way, your measurements don't take into account that the towers collapsed from the middle, not from the bottom. Suspiciously, the collapse began precisely where the planes hit, not from the bottom as they would have if they had been demolished by explosives.

Answer 4

Because in New York, everything and every person is more hard then the rest of the country, so they fall to the ground faster.

Answer 5

You've got to be kidding. You're asking about an eight tenths of a second issue based on watching an un-calibrated video clip????? This must be the answer you're looking for- it was Bush.

Answer 6

No No NO.

The correct phrase is "freefall speed into it's own footprint"!!

And you forgot to post the LINKS...

Didn't they teach you ANYTHING at the Bohemian Grove orientation?

Answer 7

Maybe the gravity of the situation lent weight to the collapse....

Answer 8

don't you just love the "get a life" cliche...it seems so perfect here........