Split Thread Was global collapse of WTC inevitable?

[Furcifer]

All we were talking about was the difference in impact force, or ability to do damage, between 1kg of loose sand and a 1kg solid weight.

ergo would you just admit you don't have enough understanding of physics to ask the right questions?

At least try to understand what you're being told.

 

[1337m4n]

I seem to recall it was you who suggested there would be little? no? difference between the impact of loose sand and the impact of an anvil on your body.

So have you tried my experiment yet?

 

[1337m4n]

Yeah, I meant they were trying to get you confused on that, arguing about KE/PE to ignore your point about the difference in impact force.

Oh, so you wanted IMPACT FORCE. Well excuse me.

In that case let's see.

Equation for IMPACT FORCE of loose particulate matter: F = Mass x Acceleration

Equation for IMPACT FORCE of a single solid mass: F = Mass x Acceleration



OH MY GOD THEY'RE STILL THE SAME

WHAT SORCERY IS THIS???

 

[excaza]

Really, excaza? Dave Rogers thought that potential energy was the critical calculation here. GlennB thinks it's impact force. Reactor drone thinks that the equation for impact force does not describe a dynamic force. He says you need to calculate impact acceleration, but doesn't want to do it.

All we were talking about was the difference in impact force, or ability to do damage, between 1kg of loose sand and a 1kg solid weight.

They're giving you different parts of the same problem. You asked what the difference in available work was between a bag of sand and loose sand. That's what Dave Rogers gave you E = mgh. Energy is the ability to do work.

The forces exerted are given by F=ma.

Those were the only 2 equations given to you. The 'impact force' is not a special force. It's still F=ma. That a is not g.

You can treat the falling debris as a solid object as long as you can make a reasonable assumption about the motion of the center of mass. Which is why I keep linking you to the wikipedia page. http://en.wikipedia.org/wiki/Center_of_mass

Your lack of comprehension is not our failure, it's yours. This is basic physics, and it's been explained to you repeatedly. Honestly I have no idea why you keep maintaining this 'rubble can't do damage' tirade when you've been shown repeatedly that it's wrong. You've seen the water crushing the car. Maybe you should take 1337m4n's advice and drop a couple hundred pounds of loose sand on your head.

 

[1337m4n]

Well, that wouldn't be accurate,

I can't wait for your convoluted explanation of why. Let's see...

as each particle has its own impact on the matter in question

Ergo, are you aware that ALL matter is made up of particles?

I guess if I drop an anvil on my head it won't hurt since it's just a collection of tiny, tiny atoms. Right?

and is subject to friction of its own

Please explain what "friction" has to do with the relative destructive power of a pound of sand vs a pound of solid iron. Show all calculations.

so you can't treat the volume of sand particles like an intact object.

Hmmmm.

Equation for IMPACT FORCE of loose particulate matter: F = Mass x Acceleration

Equation for IMPACT FORCE of a single solid mass: F = Mass x Acceleration

Actually, I can. How about that.

 

[ergo]

You asked what the difference in available work was between a bag of sand and loose sand.

No, I didn't.

Those were the only 2 equations given to you. The 'impact force' is not a special force. It's still F=ma. That a is not g.

I never said it was. And so maybe you should ask Reactor drone why he's saying that calculating the impact force is not good enough?

You can treat the falling debris as a solid object as long as you can make a reasonable assumption about the motion of the center of mass. Which is why I keep linking you to the wikipedia page. http://en.wikipedia.org/wiki/Center_of_mass

I noticed. You guys like that link a lot. But you only ever link to it.

Please explain how centre of mass for a volume of particulate matter relates to its ability to apply force on something.

Your lack of comprehension is not our failure, it's yours.

No, it isn't. Bee dunkers appear to be very confused about what they're arguing.

This is basic physics, and it's been explained to you repeatedly.

No, it hasn't. Except for ROOSD, no one here has modeled a rubble-driven collapse. You have not explained your theory of centre of mass for particulate matter. You have been shown repeatedly that particles and fragments cannot and will not be able to apply the same force on an object as a solid object of the same material. This has been explained to you repeatedly and the lot of you continue to hedge and hmm about it.

If you're going to claim that a layer of rubble can crush 80 and 90 storeys of an intact highrise in under 15 seconds you better bloody well be able to explain it. You haven't. You haven't even tried. It's an idiotic proposition and you've said absolutely nothing to make it less idiotic. Okay?

 

[excaza]

No, I didn't.

Guess you didn't...

They apparently see no difference in an object's ability to do work whether it's intact or fragmented.

Oh...

 

[excaza]

Please explain how centre of mass for a volume of particulate matter relates to its ability to apply force on something.

The use of the mass center often allows the use of simplified equations of motion, and it is a convenient reference point for many other calculations in physics, such as angular momentum or the moment of inertia. In many applications, such as orbital mechanics, objects can be replaced by point masses located at their mass centers for the purposes of analysis

I'm not sure how to make it any clearer.

You have been shown repeatedly that particles and fragments cannot and will not be able to apply the same force on an object as a solid object of the same material. This has been explained to you repeatedly and the lot of you continue to hedge and hmm about it.

You have shown absolutely nothing. You've very stubbornly made the assertion though. The same? Not in all cases, no. That doesn't mean it can't apply any force, like you're asserting.

If you're going to claim that a layer of rubble can crush 80 and 90 storeys of an intact highrise in under 15 seconds you better bloody well be able to explain it. You haven't. You haven't even tried. It's an idiotic proposition and you've said absolutely nothing to make it less idiotic. Okay?

Tell you what, since you're so convinced particulates can't do any damage, and since you don't have any actual, technical issue with the proofs already provided, do the experiment yourself. Have a backhoe drop a couple hundred pounds of loose sand on your head and let us know what happens.

 

[ergo]

You have shown absolutely nothing. You've very stubbornly made the assertion though. The same? Not in all cases, no. That doesn't mean it can't apply any force, like you're asserting.

Yes, that's exactly what I've been asserting, all this time.

 

[excaza]

Yes, that's exactly what I've been asserting, all this time.

You're asserting debris cannot do any significant damage. This is incorrect. As has been your approach in "proving" your assertion, which has been consistently, and correctly pointed out to you.

 

[Reactor drone]

No, I didn't.



I never said it was. And so maybe you should ask Reactor drone why he's saying that calculating the impact force is not good enough?

When did I say that?

I think calculating the impact force is a fine method of determining impact forces.

Figuring out what acceleration to plug into the equation can be a bitch though.

 

[Furcifer]

Please explain how centre of mass for a volume of particulate matter relates to its ability to apply force on something.

"on something"

No, it isn't. Bee dunkers appear to be very confused about what they're arguing.

No, you're confused. You keep asking the most ridiculous questions and people are trying to help you. It doesn't help that you aren't exactly...adept. Mind you, it probably doesn't help to have 8 people trying to explain things.

You have been shown repeatedly that particles and fragments cannot and will not be able to apply the same force on an object as a solid object of the same material. This has been explained to you repeatedly and the lot of you continue to hedge and hmm about it.

This again is incorrect. A liquid, or "particulate matter" can apply the same force on an object as a solid. You just don't get it yet do you

If you're going to claim that a layer of rubble can crush 80 and 90 storeys of an intact highrise in under 15 seconds you better bloody well be able to explain it. You haven't. You haven't even tried. It's an idiotic proposition and you've said absolutely nothing to make it less idiotic. Okay?

lol, a layer of guacamole and refried beans of sufficient mass could crush an 80 or 90 or 200 storey building in 15 or 25 seconds

or a layer of feathers, '76 AMC Gremlins, Elvis impersonators, golf balls, sport socks, rabid spider monkeys, magic 8 balls, paper or plastic, fish, locusts, dangling chads, old motherboards, Atari cartridges...

 

[Sam.I.Am]

Atari cartridges...

Well that explains where all of those copies of E.T. went...

 

[kylebisme]

There's no reason for doubt, it's been proven over and over ...

What are you referring to as proof specifically? The most I've seen is energy calculations and simulations using heavily simplified one dimensional models. I've yet to see even any 3D simulation to support the notion that such structures could crush themselves from the top down as the towers are claimed to have, let alone any sort of real world example to rightly prove the theory.

 

[Furcifer]

What are you referring to as proof specifically? The most I've seen is energy calculations and simulations using heavily simplified one dimensional models. I've yet to see even any 3D simulation to support the notion that such structures could crush themselves from the top down as the towers are claimed to have, let alone any sort of real world example to rightly prove the theory.

Right, because the 2 recorded for the entire world to see were rigged. Plus the half scale model as well.

What is there to understand that requires a 3D simulation? The mass of the upper section was calculated, by several people. The capacity of the damaged structure was calculated. The falling mass of the upper section was significantly greater than the capacity of the lower and the collapse continued.

The proof that it happened is that it happened, not once but twice. This is irrefutable, they fell.

Now despite everything that you haven't seen, I haven't seen a single calculation, simplified or otherwise, to suggest what happened did so only with assistance from explosives or weakening of some sort.

So there's your proof. Nobody, not 1 single person has come anywhere close to demonstrating that it couldn't have happened the way the "government" said it happened.

 

[kylebisme]

There's plenty of real world examples of controlled demolitions which show it takes a lot of assistance to bring buildings down so quickly and completely. Yet again, there's not even one simulation to support claims to the contrary, let alone a real world, just a lot of faith in the notion that it's what happened on 9/11.

 

[Furcifer]

There's plenty of real world examples of controlled demolitions which show it takes a lot of assistance to bring buildings down so quickly and completely.

I wish this had any relevance to what happened on 9/11, but aside from the fact that a building falling down due to explosives looks like a building falling down due to sustained fires, there is none. When a building falls down, it looks like a building falling down. The fact is the thunderous sound of explosives is missing from the WTC collapse. Some of you acknowledge this and say they must have been silent, some of you insist the entire population of lower Manhattan just tuned it out. The latter explanation is just ridiculous. PBS is running a program on NOVA about people trapped in elevators. They interview a guy who was actually stuck in an elevator from the first impact to seconds before the collapse. He described the sound as a "thud". Now I don't know where you stand on this issue, but arguing with people who watched it happen on a YouTube video and them insisting there was an explosion, when a guy who was in an elevator describes it as a "thud" is just maddening. There were no traditional explosives, if there was anything it would have had to have been "thermite". And thermite doesn't do anything that heat and fires didn't do anyways. Thermite is just a crutch used to attribute nefarious human causes to something that was going to happen anyways.

Yet again, there's not even one simulation to support claims to the contrary, let alone a real world, just a lot of faith in the notion that it's what happened on 9/11.

Hardly faith and I resent that. I looked into the idea that the collapse need some outside assistance, crunched some of the numbers myself, and came the resounding conclusion that you can't drop an 11 storey building 3 stories onto another building and expect it to hold up.

You can't do it. It doesn't matter how big the building is underneath it, you can't drop a building onto another building like was done on 9/11. It's not even close to possible. If you do the entire building will collapse.

In fact, if you had a fire burning in a building uncontrolled and you couldn't get water to it, the best thing to do would be to set off some explosives to try and suck the oxygen out of the fire and put it out. Or maybe, to collapse the damaged floor onto the floor below and possibly save the entire building from global collapse by stopping it from dropping 3 stories.

Unfortunately, the CD theory just doesn't come anywhere near being logical. It isn't needed to ensure the collapse, is logistically impossible and opens yourself up to all kinds of risks for no benefit whatsoever.

So take your conspiracy elsewhere, I don't really care about the rest of it. I'm just concerned with what happened at the WTC, and what happened at the WTC was exactly what we saw; two airplanes crashed into the buildings, the fires burned uncontrolled and the buildings collapsed onto themselves in a rather dramatic fashion without the need for any explosives or assistance from anything other than gravity.

 

[TruthersLie]

The avalanche example, as I've already pointed out at least twice in my short time here, is not only incorrect, but stupid. If you don't understand why then we'll just chalk that up to the fact that you're a bee dunker and probably can't.

ReallY?

I must have missed it. I'm sure you can provide a link where you explain away how an avalanche made up of loose particles can crush buildings.
or where you explained how the water managed to destroy the car. I have been away... maybe I have missed it.

please provide the citation.

you re the one who loves to handwave away how loose particles (when there are enough of them) can act like a solid and how their mass doesn't care too much about air resistance... i'm still waiting for that explanation on how that car was destroyed...

 

[triforcharity]

Yeah, you're just confusing kinetic energy with the impact force, as while the former is the same, the latter is less for the particulate matter.

Regardless, consider for a moment how typical controlled demolitions are done, the bottom third or so is blasted out so the upper section can fall far enough to accumulate the force need to crush itself on the ground below. If a section towards the middle is blasted out instead, a larger section would need to be blasted out, since the falling section would have less weight and hence have to fall farther to accumulate the force necessary to crush itself along with the remaining structure below. If a smaller section towards the top weren't blasted out at all, but rather only compromised by impact damage and fires, I doubt global collapse would be inevitable, or even possible for that matter.

The Verinage demolition technique proves you wrong.

 

[carlitos]

I realize the JREF is supposed to be an educational resource, but is it really the responsibilty of the JREF forum to teach Physics 101 to people who don't have a basic understanding of the subject?

You are talking about the August Stundie award-winning poster, who asserted the following.

I'm not sure even a moon-sized field or mountain of rubble, dropped from a height of 12 feet would entirely crush the WTC. No. If you had it coming down from a higher height, in a steady stream over a long period of time, we would certainly see some major damage. Total collapse? I'm not sure.

Keep this in mind. The ignorance appears to be willful. He is a one-trick pony, and that one trick appears to be the assertion that rubble can't damage things as much as solid chunks of stuff. No math or physics is ever provided. He keeps posting this in threads, and people keep noting avalanches and cars crushed by water, with no apparent realization of the cognitive dissonance involved. Ignore is probably your best option.

(The mass of the moon is 7.3477 × 10²² kg)