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

Originally posted by -PLB-
reply to post by ANOK

 

Sure gravity is a special kind of force that we should not count as external force. You are truly making this up while you type aren't you?

words do not suffice describing the shenanigans you employ. a few pages back, you said:

In a building collapse there is gravity, an external force.

but now your saying we shouldn't count it as external? sheer OS'er gold. your argument is invalid, as is everything you say.

reply to post by Bob Sholtz


Its called sarcasm, the last sentence is meant to make that clear. When you understand a bit of physics you understand that its total nonsense. The only reason you and anok ignore gravity as external force is because it ruins your fantasized nonsense physics, which you require to base your equally nonsensical conspiracy theory on.

Fact is, momentum and kinetic energy of falling building parts increased during almost the entire collapse.

Originally posted by -PLB-
reply to post by Bob Sholtz

 

Its called sarcasm, the last sentence is meant to make that clear. When you understand a bit of physics you understand that its total nonsense. The only reason you and anok ignore gravity as external force is because it ruins your fantasized nonsense physics, which you require to base your equally nonsensical conspiracy theory on.

LOL you're hilarious PLB, all you're doing is repeating what we've said about you, but the difference is reality supports what we're saying.

Fact is, momentum and kinetic energy of falling building parts increased during almost the entire collapse.

And you would be right as we've been saying all along. Amazing how you can never seem to get the discussion straight?

But you keep ignoring the problem with that fact. Ke and momentum can not increase against resistance. The only way that can happen is if the resistance is removed ahead of the collapse. Any amount of resistance reduces the Ke and momentum. The forces required to cause connections to fail would cause massive resistance, and again if you still want to claim the mass stayed in the footprints the floors themselves would create resistance as they stacked up and had nowhere else to fall.

Resistance reduces Ke and momentum, if they both increased either the resistance was removed, or the falling floors somehow gained extra energy that was not available from gravity. Either way it could not happen that way simply from gravity.

If you can prove otherwise put your money where your mouth is, and build a model that you can make collapse by dropping 20% of the mass on 80%. Good luck.

reply to post by -PLB-


well, there is quite a debate over whether gravity is a force or not. classic physics says it is, but current understanding says it is an illusion caused by the bending of space. kind of like a moebius strip, a two dimensional shape that bends through a third dimension.

how did the top floors of the tower survive intact almost all the way down? the force pairs would dictate that the larger mass would do more damage to the smaller mass, yet the smaller mass does more damage. it's not possible.

Originally posted by Bob Sholtz
reply to post by -PLB-

 

well, there is quite a debate over whether gravity is a force or not. classic physics says it is, but current understanding says it is an illusion caused by the bending of space. kind of like a moebius strip, a two dimensional shape that bends through a third dimension.

how did the top floors of the tower survive intact almost all the way down? the force pairs would dictate that the larger mass would do more damage to the smaller mass, yet the smaller mass does more damage. it's not possible.

I think it's less that the smaller mass is doing more damage, and more that the smaller mass is riding the collapsed debris and such all the way down. The debris is what was taking out the floors for most of the collapse. Too much weight coming down simply too fast for the supports to handle, and then those collapsed supports become more falling weight.

PLB seems to think gravity is this huge force that can overcome resistance of a solidly built structure which is nonsense.

Gravitational force is really small, for a human body it's only a few hundred Newtons.

Gravity is relatively weak because of the small value of the gravitation constant G; in metric units,

G = 6.7 x 10-11 N•m2/kg2 .

www.opencourse.info...

Compared with a steel structure gravity has so little force that it alone can not cause the floors to continue collapsing against the resistance of the structure itself.

He's just making stuff up again. Where did you go to school for electrical engineering PLB? You should sue them.

Originally posted by Varemia
I think it's less that the smaller mass is doing more damage, and more that the smaller mass is riding the collapsed debris and such all the way down. The debris is what was taking out the floors for most of the collapse. Too much weight coming down simply too fast for the supports to handle, and then those collapsed supports become more falling weight.

Too much weight is nonsense, no weight was added that the building was not designed to hold.

Speed of the falling debris is dependent on the collapse method, not the other way around as you are trying to claim.

Debris can not both stay in the footprint and cause collapse, and not be there when the collapse was complete.

You still have not addressed the laws of motion that explain how objects interact. Unless you do that you have not addressed the physics, period, you are just making stuff up.

How many times does all this have to be repeated?

reply to post by ANOK


You believe the horizontal trusses and other non-vertical supports were meant to hold vertical weight?

I believe you, sir, are mistaken.

reply to post by -PLB-

Sure gravity is a special kind of force that we should not count as external force. You are truly making this up while you type aren't you?

Gravity acts on all the objects in question at all times, it doesn't just start acting when the supports give way.

The top of the building has been accelerating towards the center of earth at 9.8m/s^2 since the 1970's. All that happened was that the resisting force amounting to 9.8m/s^2 in terms of Newton's laws was removed. When it struck the lower portion portion of the building that had been resisting the force generated by 9.8m/s^ of acceleration of a greater mass (because some mass has already been lost) since the 1970's as well.

But you think that this lower structure is now magically not able to provide this 9.8m/s^2 resistance anymore allowing the acceleration to continue.

What you are saying is that somehow the ability of the lower structure to provide the resistance it has been giving since its creation has been removed.

STOP PRESS!!!!!
SHOCKING NEWS!!!!
PLB is a TRUTHER

He believes, as do truthers, that the capacity of the lower floors to resist was removed.

So what magical mechanism do you propose if not explosives/thermite. There was no fire or plane impact on those floors, so I'm guessing you think it was termites? Agnawing buggers those things are.

Originally posted by ANOK
Ke and momentum can not increase against resistance.

This is just another chapter in your fantasized nonsense physics. You completely made this up.

The only way that can happen is if the resistance is removed ahead of the collapse. Any amount of resistance reduces the Ke and momentum. The forces required to cause connections to fail would cause massive resistance, and again if you still want to claim the mass stayed in the footprints the floors themselves would create resistance as they stacked up and had nowhere else to fall.

Resistance reduces Ke and momentum, if they both increased either the resistance was removed, or the falling floors somehow gained extra energy that was not available from gravity. Either way it could not happen that way simply from gravity.


If you can prove otherwise put your money where your mouth is, and build a model that you can make collapse by dropping 20% of the mass on 80%. Good luck.

It is explained to you many times why this is wrong. It is about net force. If average resistance is lower than the average force of the falling mass (as result of gravity accelerating it) there is increase in momentum and there is acceleration. When you are asked to demonstrate that resistance is too high using calculations you repeat your "conservation of momentum" line again. Anyway, I am not wasting any more of my time on you with any detailed explanation.

Originally posted by Bob Sholtz
reply to post by -PLB-

 

well, there is quite a debate over whether gravity is a force or not. classic physics says it is, but current understanding says it is an illusion caused by the bending of space. kind of like a moebius strip, a two dimensional shape that bends through a third dimension.

how did the top floors of the tower survive intact almost all the way down? the force pairs would dictate that the larger mass would do more damage to the smaller mass, yet the smaller mass does more damage. it's not possible.

Oh come on, you are talking about theoretical physics. For any practical application gravity is a force. You are really trying to throw anything at the wall and hope it sticks. Bottom line is that you are wrong, you do not understand the physics.

Your second question is also answered many times on this forum. Between the top section and bottom section, the already collapsed floors form a buffer. This buffer has the mass of all collapsed floors combined, minus any debris that fell aside. This mass alone can demolish lower floors, without any top section. So I will ask you a question, which floor has to suffer the most, a floor in the lower section which has all failed floors falling on it plus the weight of the top section, or the floor in the top section which only has to suffer the weight of the top section?

I know it is usual that truthers now claim that all the collapsed floors were ejected. Just to be one step ahead, that is a truther fantasy that has absolutely no basis in reality. When you ask any truther making this claim to prove it, you are attacked with a wall of silence. Anok sometimes posts an FEMA diagram showing circles how far the debris fell. He thinks that somehow proves that almost all the floors ejected, even after it is explained (many times) to him that it were the perimeter columns that fell that far. Lets hope you are a bit less blinded by your conviction, and understand that ejecting floors is just nonsense.

Originally posted by Darkwing01
But you think that this lower structure is now magically not able to provide this 9.8m/s^2 resistance anymore allowing the acceleration to continue.

Take a plate, and put a brick on it and wait for an hour. Then pick up the brick 50cm and let it drop on the plate. What? The same plate that has been resisting the brick over an hour now fails . Is it magic?

What you are saying is that somehow the ability of the lower structure to provide the resistance it has been giving since its creation has been removed.

Nope, that is you not understanding the physics. The resistance sure was lower, as the top section did not fall exactly on the support columns, which offered the most resistance (the support columns is what used to hold the top section all that time). But what is even more important is that the dynamic load as result of the top gaining velocity is magnitudes greater than the static load. That is also the reason why your plate didn't break when you laid the brick on it, but did brake when you dropped in from a height.

STOP PRESS!!!!!
SHOCKING NEWS!!!!
PLB is a TRUTHER

He believes, as do truthers, that the capacity of the lower floors to resist was removed.

So what magical mechanism do you propose if not explosives/thermite. There was no fire or plane impact on those floors, so I'm guessing you think it was termites? Agnawing buggers those things are.

So now that I explained it to you, what are you going to do? Ignore the explanation or try to understand it? I know the answer already because we discussed this stuff before.

OK take a look at this, a demonstration of how mass and velocity effects colliding objects.

I used a big red truck doing 10mph, and a scooter doing 90mph, to give you a good exaggerated example. This was the result...

The red truck came into the collision at 4.47 meters per second (10.00 miles per hour)
It left moving at 4.45 meters per second (9.96 miles per hour)
It hardly lost any speed at all!

The scooter came into the collision at -40.23 meters per second (-90.00 miles per hour)
It left moving at 49.16 meters per second (109.96 miles per hour)
It was jolted so much by the collision that it was sent back in the opposite direction!

Notice the truck hardly moved, but the scooter was accelerated backwards at 109.96 MPH. In the real world, with momentum conservation considered, the scooter would be crushed, and the truck would receive very little damage.

Now two trucks at 90MPH...

The red truck came into the collision at 40.23 meters per second (90.00 miles per hour)
It left moving at -40.23 meters per second (-90.00 miles per hour)
It was jolted so much by the collision that it was sent back in the opposite direction!

The red truck came into the collision at -40.23 meters per second (-90.00 miles per hour)
It left moving at 40.23 meters per second (90.00 miles per hour)
It was jolted so much by the collision that it was sent back in the opposite direction!

Notice they create equal responses? Equal mass, equal damage.

Now put that in context of floors impacting floors, are you smart enough to realise what would happen? 15 floors can not crush 95 just like the scooter can not crush the truck.

This is basic physics.

Such a childlike to view to assume you can make valid conclusions about the collapse of the WTCs via a basic thought experiment involving two colliding trucks.

Get real, man.

Experts have weighed in with pages of complex equations to explain the physics, you are really out of your depth with this arm-chair physicist nonsense.

reply to post by -PLB-

Take a plate, and put a brick on it and wait for an hour. Then pick up the brick 50cm and let it drop on the plate. What? The same plate that has been resisting the brick over an hour now fails . Is it magic?

Lol, I never said it wouldn't break.

I said it would decelerate.

Does it decelerate PLB? Well? Does it?

By the way ANOK, just one of the ways your analogy fails is that colliding trucks are separate structures, moving towards each other. Neither of these facts are analogous to the WTC floors. We have to factor in weakening and damage to existing floors, too.

The real world does not work in such absolute terms, there are so many factors to take into account, that's why NIST and other experts wouldn't think to make a conclusion about the collapse in such ridiculously simple terms.

Originally posted by humphreysjim
Such a childlike to view to assume you can make valid conclusions about the collapse of the WTCs via a basic thought experiment involving two colliding trucks.

Get real, man.

Experts have weighed in with pages of complex equations to explain the physics, you are really out of your depth with this arm-chair physicist nonsense.

Get real? You need to get real. What I posted was a perfectly relevant demonstration of the reaction of two colliding bodies. THOSE LAWS APPLY TO ALL COLLIDING BODIES. If you can't put it into context with falling floors, then that is your stupidity showing, nothing more, nothing less. Those laws do not change because it's concrete floors, and not other objects. The big red truck is 95 concrete floors, the scooter is the 15 floors with momentum.

Your 'experts' are shills.

ATS DENY IGNORANCE.

God I'm sick of this crap with you guys.

reply to post by Darkwing01


You confuse deceleration with a lower acceleration. There are 3 options. The acting force is larger than average resistance: acceleration. The acting force is equal to average resistance: constant speed. The acting force is smaller than average resistance: deceleration.

So what you need to show, using physics and math, is that the average resistance is equal or greater than the acting force. If it is not, there will be a net acceleration. So you need to know the resistance. This is very complex to determine. I have yet to see anyone make a realistic approximation. Obviously no truther has done so either. All we ever hear is baseless assertions based on general ignorance of physics.

reply to post by ANOK


It has been told to you over and over that a collapsing building does not behave like two colliding bodies, so your model can be thrown in the bin. All you examples are completely irrelevant.

reply to post by -PLB-

There are 3 options. The acting force is larger than average resistance: acceleration. The acting force is equal to average resistance: constant speed. The acting force is smaller than average resistance: deceleration.

Force is MASS times ACCELERATION.

F=ma

Do you see kinetic energy or velocity in that calculation PLB, because I sure don't. Perhaps you should contact Newton and inform him of his error because WTC sure proved that velocity should be in there..... Or not....

The acceleration of the body was 9.8m/s^2 in 1970, it was 9.8m/s^2 when it the planes hit. It was 9.8m/s^2 when the supports failed. I was 9.8m/s^2 when it fell one whole story. It was 9.8m/s^2 when it impacted the lower story. It was 9.8m/s^2 when the lower story failed.

Do you see velocity anywhere in there? I sure don't.

The lower structure was resisting that mass at that acceleration, in fact was was capable of resisting twice to three times that. The only way that can overcome the resistance is by slowing the original mass down (decelerating it).

You can observe this in countless impacts and Verinage demolitions, to deny it is to deny reality.

____________________________________________________________________________________________

Take those concrete slabs you were talking about earlier, now take the broken slab and drop it the same distance on another concrete slab. Does it still break?

Can you see why it doesn't?