The Twin Towers at free fall speed

[Mancman]

I didn't know this. (Putting aside that speed is measured in m/s, not s)

Free fall time of a heavy, small surface object, from 400m:

g=h/dt²
dt=(h/g)^-2=(400/9.8)^-2=6.4s

That's the time it would take a heavy, small surface object to reach the ground from 400m. That's free fall.
The speed (velocity) of the object increases during the whole event. v=g*dt. Velocity just before impact: 9.8*6.4=62.72m/s= 225 km/h.

(excuse me folks, I'm having a high school flashback moment here)

You're supposed to double the height in this equation, answer would be 9.0s.

 

[dio]

You're supposed to double the height in this equation, answer would be 9.0s.

I stand corrected. 9s indeed.

 

[dropzone]

I'm still working on the cheerleaders and will be for some time. Remind me to not tell you of an importune moment in Algebra class. Though that was 40 years ago. Some memories linger.

 

[bardamu]

And this makes it fall faster... how?

It doesn't fall faster. It begins falling earlier.

 

[GlennB]

It doesn't fall faster. It begins falling earlier.

This would make sense theoretically.
In reality we see a synchronised collapse occuring over 3 floors or so. Large pieces start falling off after the main collapse front is under way, not before.

 

[TruthersLie]

It doesn't fall faster. It begins falling earlier.

Is that all you have? arguments from ignorance?

Take any decent video of the collapse.

You see the walls collapsing, those are falling FASTER than the collapse of the towers.

They aren't falling longer. Pieces from the SAME place are moving faster.

that clearly shows that it is NOT at freefall.

massive swing, massive miss.

(does it hurt to get owned so often in so many ways?)

 

[McHrozni]

--

 

[johnny karate]

It doesn't fall faster. It begins falling earlier.

Okay...

And yet you offered this response:

Maybe the debris was from the upper block, part of which was destroyed before the main destruction front began to move downward.

...to this question (emphasis mine):

If it was falling at "Free-fall" why was the debris falling faster (as seen in the videos)?

Do you read what you're responding to before posting?

 

[cyclonic]

Shouldn't the speed of free fall be from the area from where the collapse began not how tall the buildings are?

Exactly right, here is my copy and paste response i use for the twoofers.

freefall speed facts.

if weight dropped from 110 floor to ground level : 9.2 secs.
wtc2 30 top floors fall from 80th floor to ground level :15 secs.
wtc1 top 15 floors fall from 95 th floor to ground level: 22secs

freefall is another truther lie.

Now can anyone work out if weight dropped from 47th floor to ground level how long that would take?

 

[Thunder]

i may be the first to say this, but with those damn clouds of debris blocking the view at the bottom, it is kinda impossible to know for sure exactly how long it took the towers to completely collapse.

 

[BigAl]

i may be the first to say this, but with those damn clouds of debris blocking the view at the bottom, it is kinda impossible to know for sure exactly how long it took the towers to completely collapse.

Seismic data was used to establish the end point. From one of the NIST FAQs:

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)? 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)... [2]

 

[jay howard]

Exactly right, here is my copy and paste response i use for the twoofers.

freefall speed facts.

if weight dropped from 110 floor to ground level : 9.2 secs.
wtc2 30 top floors fall from 80th floor to ground level :15 secs.
wtc1 top 15 floors fall from 95 th floor to ground level: 22secs

freefall is another truther lie.

Now can anyone work out if weight dropped from 47th floor to ground level how long that would take?

This is the NIST (you remember those guys) official explanation with my emphasis:

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)?

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.

From video evidence, significant portions of the cores of both buildings (roughly 60 stories of WTC 1 and 40 stories of WTC 2) are known to have stood 15 to 25 seconds after collapse initiation before they, too, began to collapse. Neither the duration of the seismic records nor video evidence (due to obstruction of view caused by debris clouds) are reliable indicators of the total time it took for each building to collapse completely.

Whatever the interpretation of the speeds of collapse, NIST is unequivocal about the amount of time it took.



.

 

[jay howard]

Big Al beat me to it.

 

[daws59]

Well, mine usually involve naked cheerleaders, but you're definitely welcome to your flashback moments too

naked cheerleaders in a smoke filled van!... not a fantasy!

 

[dio]

Well, since my recollection of the high school free fall equation was wrong, now I'm not so sure about your naked cheerleaders memories either, guys.

 

[daws59]

Well, since my recollection of the high school free fall equation was wrong, now I'm not so sure about your naked cheerleaders memories either, guys.

I still have the scars!...talk about free fall!

 

[TruthersLie]

This is the NIST (you remember those guys) official explanation with my emphasis:




Whatever the interpretation of the speeds of collapse, NIST is unequivocal about the amount of time it took.



.

The amount of time it took for

elapsed times for the first exterior panels to strike the

That is NOT the full collapse time. Which is longer. The full collapse time was over 15 seconds on the first tower and over 20 seconds on the second one.

The first outer columns broke away and WERE falling at freefall, as opposed to the collapse.

that alone is proof that there was NO freefall

 

[Edx]

The amount of time it took for


That is NOT the full collapse time. Which is longer. The full collapse time was over 15 seconds on the first tower and over 20 seconds on the second one.

The first outer columns broke away and WERE falling at freefall, as opposed to the collapse.

that alone is proof that there was NO freefall

Can you believe some truthers use that NIST quote to show NIST admits it is nearly the times they say it is? (about 10-11 seconds)? When it actually shows the complete opposite due to that sentence they ignore. lol

 

[cyclonic]

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

.

 

[Bluesky]

Nice Cyclonic... very clearly shows that WTC1 and 2 collapse at way less than freefall speed.

So why doesn't Richard Gage and his 9/11 truth cult admit this fact and try and work their lunatic theory around some honest observations? Truthers cant pretend he hasnt seen these.

If the fall took 14.5 seconds, which is the fast end of your range then the collapse took place at 40%g. So a large part of the potential energy was not converted into kinetic energy implying there was substantial resistance.

Why do they lie.? Can any truther on this forum explain?