Outside energy had to be introduced for the twin towers to collapse the way they did

Originally posted by seachange

So in your belief if I use the 800,000 ton figure I'm a complete idiot, but apparently if I use your number I'm a genius.

No.

Merely informed.

What you SHOULD have said if you had any shred of respect, and you don't, would be "you're wrong about how much concrete".

And on the flip side, you shoulda known these facts before weighing in.

And more importantly, you should have cited a source for your numbers.

It's common knowledge.

I suggest you go to Jim Hoffman's site here:

911research.wtc7.net...

He's a truther.

Originally posted by waypastvne

Originally posted by Bob Sholtz
the equation i just posted is F=ma. it's the same equation i've been using this whole time. care to say it's wrong? there are two masses, bottom subtracted from top, times 9.8m/s = force. it comes out negative, which means the top cannot destroy the bottom.

F=ma is a very sensible equation, and every person who has completed high school physics would laugh at you if they saw what you just posted.

Let me make it easy for you and give you multiple guess question.

What exactly do you think the "a" in F=ma represents ?

(A) 9.8

(B) the rate of change of velocity with time.

(C) Potato

you do realize that "a" is multiplied by both masses, right? so it could equal potato and the result would be the same. m1-m2 ALL multiplied by "a". it is constant and the same for both the falling and impacted floors.

i don't understand what you're not getting.

reply to post by Joey Canoli

The vertical rsistance of the columns was mostly bypassed, since stuff falls on floors, not columns.

here lies the problem. they weren't left standing, and neither were the sides. if the floors were falling through a giant tube, why are the core columns and the tube broken at the same rate the floor is?

you can't have it both ways. either the core columns resisted, or they didn't. you can't say "vertical resistance was mostly bypassed" then say they were destroyed by taking hits from multiple directions.

Remember, the "OS" states that the core column strength was bypassed for the most part.

i ask again, where are they? if the floors falling missed them, AND they get dramatically thicker towards the bottom, where are they? none of them fell over, and none were left standing. you can't have it both ways.

Originally posted by Bob Sholtz

here lies the problem. they weren't left standing, and neither were the sides. if the floors were falling through a giant tube, why are the core columns and the tube broken at the same rate the floor is?

Actually, the cores did remain standing, at least for a few moments after the floors and exterior collapsed. What remained behind the was lowest sections of the core. The rest either A) collapsed as part of the first section to let go or B) destroyed by the upper section collapsing. That is why we saw the Spire so tall for the North Tower, and half of the core for WTC2. As for the exterior columns, well, they got pushed out and over by the force of the collapsing floors AND the top section falling on them.

you can't have it both ways. either the core columns resisted, or they didn't. you can't say "vertical resistance was mostly bypassed" then say they were destroyed by taking hits from multiple directions.

The core columns were just giving the resistance where the floor truss seats were located. That's it. Vertical resistance was mostly done by the truss seats. The columns were negligible in this collapse. Many were snapped off at the connections, others were bent over by the force. Still others may have snapped apart. But overall, in regards to the floors, they only had the vertical resistance at the ends with the seats. Nothing else.

i ask again, where are they? if the floors falling missed them, AND they get dramatically thicker towards the bottom, where are they? none of them fell over, and none were left standing. you can't have it both ways.

The core columns were in the rubble. Didnt you notice them? The floors did miss them, then when they were left standing, they fell over from either damage, or winds, or both. To say they didnt fall over is a laugh, because we can see they did. Look at this video for the North Tower. Pay very close attention to the center of the building and the parts falling over:

In the far left side of the collapse cloud, you can see long columns falling over out of the dust, and the core columns swaying as well. You can see a section of columns tilting over and snapping off. The Spire itself collapses probably when towards the base, the debris collapsing knocks over a lower segment knocking it out of the way, causing the rest to appear to fall down.

At the base, a section of the core did survive. Recall the "miracle" stairwell. People survived in the stairwells inside the core.

reply to post by GenRadek

In the far left side of the collapse cloud, you can see long columns falling over out of the dust, and the core columns swaying as well. You can see a section of columns tilting over and snapping off. The Spire itself collapses probably when towards the base, the debris collapsing knocks over a lower segment knocking it out of the way, causing the rest to appear to fall down.

i don't know what you're looking at, but the spire disintegrates into dust.

Originally posted by Bob Sholtz
reply to post by GenRadek

 

In the far left side of the collapse cloud, you can see long columns falling over out of the dust, and the core columns swaying as well. You can see a section of columns tilting over and snapping off. The Spire itself collapses probably when towards the base, the debris collapsing knocks over a lower segment knocking it out of the way, causing the rest to appear to fall down.

i don't know what you're looking at, but the spire disintegrates into dust.

No what you see is the dust that was on the spire the video quality is so low you dont see all the detail its like the videos of the disappearing wing!

Originally posted by wmd_2008
No what you see is the dust that was on the spire the video quality is so low you dont see all the detail its like the videos of the disappearing wing!

That old claim is nonsense for many reasons.

For one, no steel column is going to fall straight down, it will fall in an arc at the point of failure.

Secondly, why would the dust not just follow the column? Why was there so much dust on a column that had just been stripped of all that was attached to it? Wouldn't the dust have all been knocked off already?

Thirdly, where do you see the column as it falls? Why do we not see it fall? We simply see it start to fall, straight down, and then suddenly nothing but dust.

Fourthly, steel columns do not fall straight down.

Fifthly, steel columns do not fall straight down.

The videos are fine, you are not an expert on video quality, you are simply blindly repeating nonsense that has been claimed for years.

Originally posted by ANOK

Why was there so much dust on a column that had just been stripped of all that was attached to it? .

The core columns were covered with spray on fireproofing 2" thick. It would be hard to completely strip all of the fireproofing off of an I beam.

Originally posted by ANOK
reply to post by -PLB-

 

Not too lazy, I just know it isn't there to find, so why should I waste my time?

Where in those posts do you mention the laws of motion? Or momentum conservation, or action-reaction law?

Huh?

You didn't.

Right, you already know its not there without looking.

All I can see on that page is the same thing happening here, you ignore the laws of physics completely in order to make claims that do not abide by those laws.

An explanation of the physics that doesn't address those laws is not a valid explanation.

I asked you to explain those physical laws as they relate to the collapses, you have not done that PLB. If you think you did then you are in lala land.


So what is it I am ignoring exactly, your lame attempt to explain a physical act without mentioning the actual laws that physics abides by? All you do is explain things from a layman's point of view. You can't explain those laws because you either do not understand them, or you know it contradicts your claims. Your tactics might work with layman but I am not one of those, so you need to step up to the challenge PLB, and take your claims into the realm of higher education and reality.

I don't want to hear what you think happened, I want an explanation using the laws of motion. Unless you do that you have not addressed the physics of the collapses, period. Is that so hard to understand?

Yup, laymen explanation targeted to laymen. Now show it to be wrong using the laws of motion, so show some actual calculations.. Fact: this will never happen. You don't understand physics and math scares you.

Originally posted by Bob Sholtz

you do realize that "a" is multiplied by both masses, right?

That value is different for the stationary lower part of the tower vs the moving part.

Net acceleration of the lower part is zero.

Net acceleration is up to 9.8m/s/s.

Fix those and start over.

Originally posted by Bob Sholtz

here lies the problem. they weren't left standing, and neither were the sides.

Nor were they crushed by the falling debris.

The "spires" videos proves this for the core columns. As does the noticeable lack of buckled/crushed/whatever you are claiming core columns in post collapse photos.

Numerous pics of various sized sheets of the ext columns falling ahead of the collapse front proves that they weren't buckled/crushed/whatever you are claiming happened either. As does the multitude of overhead photos showing ext panels peeled off and in recognizable sheets lying on the ground. Most noticeable of those is the one that peeled off all the way to the Winter Garden.

if the floors were falling through a giant tube, why are the core columns and the tube broken at the same rate the floor is?

Rate?

Broken?

Yes, they were broken off. And not buckled/crushed/whatever you are claiming....

you can't have it both ways. either the core columns resisted, or they didn't. you can't say "vertical resistance was mostly bypassed" then say they were destroyed by taking hits from multiple directions.

Then I'll have to go with option 3.

The only resistance that the columns could possibly provide was:
1- limited by the strength of the floor to column connections
2- limited by the very low probability that debrise fell on TOP of a column.
3- limited by some friction factor of debris hitting them from the side and sliding down the length.

i ask again, where are they? if the floors falling missed them, AND they get dramatically thicker towards the bottom, where are they? none of them fell over, and none were left standing. you can't have it both ways.

Reality based explanations are not limited to your scenario.

Ext columns peeled off after losing their floor connections.

Floors inside the core took damage too, and were broken off. This left many long unbraced columns that were not able to sustain much swaying. The "spire" videos show exactly this. 40-50 story columns with damaged bracing swaying as a result of the debris passage. They sway to one side, and the welds that hold the column sections together break, since as I noted earlier, they were only 1/3 - 1/2 depth penetration, making them the weakest link.

Originally posted by Bob Sholtz
reply to post by GenRadek

 

In the far left side of the collapse cloud, you can see long columns falling over out of the dust, and the core columns swaying as well. You can see a section of columns tilting over and snapping off. The Spire itself collapses probably when towards the base, the debris collapsing knocks over a lower segment knocking it out of the way, causing the rest to appear to fall down.

i don't know what you're looking at, but the spire disintegrates into dust.

Disintegrates?

It fell out of frame Bob.

Originally posted by ANOK

Thirdly, where do you see the column as it falls? Why do we not see it fall? We simply see it start to fall, straight down, and then suddenly nothing but dust.

This is nothing but fantasy based belief.

Even Steven Jones realizes the absurdity of claiming this....

Originally posted by Joey Canoli

Originally posted by Bob Sholtz

you do realize that "a" is multiplied by both masses, right?

That value is different for the stationary lower part of the tower vs the moving part.

Net acceleration of the lower part is zero.

Net acceleration (oops, of the upper, moving part of the towers) is up to 9.8m/s/s.

Fix those and start over.

FTFM

EDIT

Originally posted by Joey Canoli

That value is different for the stationary lower part of the tower vs the moving part.

Net acceleration of the lower part is zero.

Net acceleration is up to 9.8m/s/s.

Fix those and start over.

Do you know what a free body diagram is? Do you understand that the analysis being discussed (an application of Newton's third law) applies to the forces operating at an idealized single point of contact between the falling top and the stationary bottom?

Also, do you understand that F=ma means that the net force acting on a system traveling at a constant speed of 50 trillion miles per second is the same as the net force acting on that same system when it is not moving at all? Namely, zero.

Now, let us assume, to the benefit of the OS, that the "bottom block" was designed only to hold the weight of the top block when it was completely empty, and that the weight of the top block was x. The force acting on that top block would be F=ma=xg~=9.8x. We can agree that the net acceleration of the point of contact between the "bottom block" and the "top block" of the building on September 10th, 2001 was zero. The building wasn't moving, thus it's velocity was zero, thus it's acceleration was 0, thus 0 netforce is acting on that point of contact at that time.

Now, let us assume that on September 11, 2001 the bottom floor of the top block magically disappears, and the rest of it falls onto the bottom block completely unimpeded. It falls with an acceleration of g, or ~9.8 m/s^2. It does not matter if it's velocity was 0, 100, or 1 trillion m/s at the point of impact. It's acceleration is CONSTANT at that point...namely ~9.8 m/s^2.

Once again, we create our free body diagram of the point where the top and bottom blocks meet after the fall of one floor. The forces acting on that point are 9.8x acting in the positive, downward direction (an overestimation, again to the benefit of the OS, as it includes the mass of the floor which we magically disappeared) and at least 9.8x acting in the negative, upward direction. Keep in mind, forces are vectors. They have a directional component and a magnitude. We created our hypothetical free body diagram with the vertical axis parallel to the direction of the force of gravity, with positive forces acting downward...which is conventional.

What this means is that the net force acting at the point of impact must be negative. This means that the acceleration of the system is negative, as mass cannot be negative. A negative acceleration means that after the initial impact between the blocks, the velocity of the "collapse" would slow down.

Direct visual evidence exists in the videos which show that the velocity of collapse did not decrease after the initial "impact". This means that the bottom "block" either somehow lost it's ability to resist the exact same forces it resisted the day before without incident, or that the "top block" somehow increased in mass or had another vertical force acting on it in a downward direction.

So which is it?


tl;dr

At the initial point of contact between the falling "top block" and stationary "bottom block", we can construct a free body diagram and measure the net force acting on the system. This net force must be negative if we are to believe the OS when it says that only gravity was acting on the system after collapse initiation, thus the system should decelerate. The system did not decelerate, and therefore the OS is not a valid explanation of the "collapse".

Originally posted by joemelon
Now, let us assume that on September 11, 2001 the bottom floor of the top block magically disappears, and the rest of it falls onto the bottom block completely unimpeded. It falls with an acceleration of g, or ~9.8 m/s^2. It does not matter if it's velocity was 0, 100, or 1 trillion m/s at the point of impact. It's acceleration is CONSTANT at that point...namely ~9.8 m/s^2.

You are not the first truther who does not understand what impact forces are. Impact forces are dependent on impact velocity, and have nothing to do with gravity. The "a" is determined by the deceleration as result of the collision. The higher the impact velocity, the higher the deceleration, the higher the force.

Once again, we create our free body diagram of the point where the top and bottom blocks meet after the fall of one floor. The forces acting on that point are 9.8x acting in the positive, downward direction (an overestimation, again to the benefit of the OS, as it includes the mass of the floor which we magically disappeared) and at least 9.8x acting in the negative, upward direction. Keep in mind, forces are vectors. They have a directional component and a magnitude. We created our hypothetical free body diagram with the vertical axis parallel to the direction of the force of gravity, with positive forces acting downward...which is conventional.

Why don't you post your FBD, then others can point out why it is wrong.

Originally posted by joemelon

Do you know what a free body diagram is? Do you understand that the analysis being discussed (an application of Newton's third law) applies to the forces operating at an idealized single point of contact between the falling top and the stationary bottom?

Also, do you understand that F=ma means that the net force acting on a system traveling at a constant speed of 50 trillion miles per second is the same as the net force acting on that same system when it is not moving at all? Namely, zero.

Now, let us assume, to the benefit of the OS, that the "bottom block" was designed only to hold the weight of the top block when it was completely empty, and that the weight of the top block was x. The force acting on that top block would be F=ma=xg~=9.8x. We can agree that the net acceleration of the point of contact between the "bottom block" and the "top block" of the building on September 10th, 2001 was zero. The building wasn't moving, thus it's velocity was zero, thus it's acceleration was 0, thus 0 netforce is acting on that point of contact at that time.

Now, let us assume that on September 11, 2001 the bottom floor of the top block magically disappears, and the rest of it falls onto the bottom block completely unimpeded. It falls with an acceleration of g, or ~9.8 m/s^2. It does not matter if it's velocity was 0, 100, or 1 trillion m/s at the point of impact. It's acceleration is CONSTANT at that point...namely ~9.8 m/s^2.

Once again, we create our free body diagram of the point where the top and bottom blocks meet after the fall of one floor. The forces acting on that point are 9.8x acting in the positive, downward direction (an overestimation, again to the benefit of the OS, as it includes the mass of the floor which we magically disappeared) and at least 9.8x acting in the negative, upward direction. Keep in mind, forces are vectors. They have a directional component and a magnitude. We created our hypothetical free body diagram with the vertical axis parallel to the direction of the force of gravity, with positive forces acting downward...which is conventional.

What this means is that the net force acting at the point of impact must be negative. This means that the acceleration of the system is negative, as mass cannot be negative.

A negative acceleration means that after the initial impact between the blocks, the velocity of the "collapse" would slow down.

Direct visual evidence exists in the videos which show that the velocity of collapse did not decrease after the initial "impact". This means that the bottom "block" either somehow lost it's ability to resist the exact same forces it resisted the day before without incident, or that the "top block" somehow increased in mass or had another vertical force acting on it in a downward direction.

So which is it?


tl;dr

At the initial point of contact between the falling "top block" and stationary "bottom block", we can construct a free body diagram and measure the net force acting on the system. This net force must be negative if we are to believe the OS when it says that only gravity was acting on the system after collapse initiation, thus the system should decelerate. The system did not decelerate, and therefore the OS is not a valid explanation of the "collapse".

In the high lighted sentence above I have pointed out the "a" in F=ma that Bob Sholts doesn't understand, and totally left out of his equation. The impact "a". This is the "a" we are interested in.

So tell us... what you think should have happened when the top block made contact with the lower block.

Please be specific, tell us what velocity you think it should be traveling when it made contact.

The velocity you think it should be traveling after it made contact.

The time you think it should take to go from the first velocity to the second.

From these speculative numbers based on what you think should happen, we can do a F=ma calculation and put some numbers on the impact force the lower portion of the building would need to withstand.

This invitation is for all Truthers. You don't have to do any math, just give us your numbers.

@ joemelon

The buildings collapsed at only 65 % of free fall acceleration, in other words they did slow down.

Originally posted by waypastvne

@ joemelon

The buildings collapsed at only 65 % of free fall acceleration, in other words they did slow down.

His whole argument is based on Szamboti's delusions.

He is unable to discern between true decel and lesser than G accel.

Originally posted by waypastvne
So tell us... what you think should have happened when the top block made contact with the lower block.

This has been explained so many times you are just being purposely ignorant, pretending there has been no explanation.

There would be an equal opposite reaction, the forces on both impacting floors would be equal, the same.

The velocity of the falling block would impart a force on the static block, the static block would impart the same force back, equal opposite reaction.

You have a 15 floors block hitting a 95 floor block. Again the first impacting floors would both receive the same force. There is less mass falling than you have pushing back. There is nothing that would keep the first floor of the falling block from failing along with the first static floor it hits. The force of the 14 floors above the first impacting floor would put force on that floor also, not just the top floors of the static block that it hits.

Consider the laws of motion, and there is no way 15 floors can crush 95 floors to the ground. If all that happened was the bolts were sheared, then the floors would still be in the footprint stacked up. You need energy to shear bolts, AND more energy would be needed to also crush floors. There is a serious problem with that because energy was lost, not gained, due to deformation, heat, sound, friction/resistance etc. For the collapse to have been complete either Ke would have had to have been increased, or an energy source that has not been addressed caused the resistance to be removed ahead of the collapse wave. There was no fire ahead of the collapse wave to weaken any steel.

'So tell us... what you think should have happened when the top block made contact with the lower block.'

Wait a minute. The top block made contact with the lower block? Are you certain of this? Really? Are you sure the top block made contact with the lower block? What proof of this do you have? Aren't you just assuming that?

I mean if outside energy was used then what's really falling on what exactly? Is anything even really "falling" on anything? I mean other than everything just falling on the street.

I guess Physics is not my strong suit.

Cheers