"Now, femr2, the next thing I want from you, here or anywhere, is an acknowledgment that you understand the above."
You are saying that you do not understand.
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Hardfire: Physics of 9/11
- Thread starter R.Mackey
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"Now, femr2, the next thing I want from you, here or anywhere, is an acknowledgment that you understand the above."
You are saying that you do not understand.
Furcifer
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Oh really? You think they're not free? Why aren't they free? I say they are free. Prove me wrong.
(sigh, I hope this works guys)
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Well if you and Ryan have found a way of accelerating 2.47e6 Kg of mass from rest to 7.96m/s without expending any energy, then I suggest you patent it smartish and get some vehicles on the road.
Well if you and Ryan have found a way of accelerating 2.47e6 Kg of mass from rest to 7.96m/s without expending any energy, then I suggest you patent it smartish and get some vehicles on the road.
R.Mackey said:
A W Smith
Philosopher
Well if you and Ryan have found a way of accelerating 2.47e6 Kg of mass from rest to 7.96m/s without expending any energy, then I suggest you patent it smartish and get some vehicles on the road.
I accounted for that energy. I showed it to you in the most elementary explanation I can manage. Apparently that wasn't enough.
Anyway, we're done here. I encourage you to seek remedial physics instruction -- elsewhere, since you clearly aren't getting what you need here. And welcome to Ignore.
Further discussion of Physics 101 is probably off-topic. Since I won't be reading these messages anymore, I won't be reporting them, but for the rest who are trying to get some value from this thread, it's your call.
Furcifer
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Well if you and Ryan have found a way of accelerating 2.47e6 Kg of mass from rest to 7.96m/s without expending any energy, then I suggest you patent it smartish and get some vehicles on the road.
It seems rather ineffcient to spend 100000 man hours and $1 Billion dollars to raise it to that height. Now you're forgetting U=mgh in your conservation of momentum equation.
I'll explain this too, in the hopes you catch on. Place two balls on a smooth level surface 3.6m apart. Now wait for the collision....Nothing yet eh? Why? Let's check energy. Potential? nope, they are both on the ground, h=0. Kinetic? Nope, not moving. Spring? Well they are made of rubber, but they aren't compressed so no. So we have a system with 0 energy. That's why we don't have a collision.
Now, what if I raise one of the balls 3.6m directly above the other one on a ledge. Do you see where we are going yet? I hope so. In raising the ball 3.6m I expended chemical energy. I ate an apple. That's the energy that allowed me to move the ball 3.6m. Now the ball is 3.6m up on the ledge, it's potential energy is stored. Now we remove the ledge (without touching the ball of course) and it falls. Bang, the balls hit. I know you can do the math here, assume the ball is 36.67 e6 Kg.
Do you understand yet? The energy moving 36.67 e6 Kg to a height of 300m isn't free. You've just forgot about it. It probably happened well before you were born.
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Newtons Bit
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Conservation of Energy states that:
Energy1 = Energy2
Or, less simply:
Potential Energy1 + Kinetic Energy1 + Strain Energy1 + Heat Energy1 + Audio Energy1 = Potential Energy2 + Kinetic Energy2 + Strain Energy2 + Heat Energy2 + Audio Energy2
Can you explain how your quoted post doesn't violate this simple law?
Furcifer
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@femr2
I just realized you should stop using the term "sinks". It isn't good. You think if it is "sunk" it's gone. When you "sink" a ship, it isn't gone, it's just moved from one place to another. Same thing with energy, when you "sink" it, you move it from one place to another or one form to another. It can't go away because the laws of thermodynamics won't allow it.
I just realized you should stop using the term "sinks". It isn't good. You think if it is "sunk" it's gone. When you "sink" a ship, it isn't gone, it's just moved from one place to another. Same thing with energy, when you "sink" it, you move it from one place to another or one form to another. It can't go away because the laws of thermodynamics won't allow it.
alienentity
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Well guys, I warned you this guy was resistant to the learning process. I was unable to convince him that there was sufficient gravitational potential energy, even when I supplied estimates, to deflect some heavy debris fairly large distances.
He's convinced that only explosives could have done this......dumb and dumber.
Thanks for your calcs everyone. At least I learned something, even if he didn't.
He's convinced that only explosives could have done this......dumb and dumber.
Thanks for your calcs everyone. At least I learned something, even if he didn't.
It is clear that I do not agree with the point being discussed, however, I see no reason for it to get in the way of progression.
I have added a switch to the new version of the model, allowing usage of the energy 'loss' through the conservation of momentum calculation to be used post impact, with one caveat:
The final velocity of the pile-driving mass cannot exceed the post impact velocity.
In situations where the calculated energy expenditure does not exceed the additional energy, the final velocity is limited to the post impact velocity, and the remaining energy assumed to be consumed by further material destruction (ie smaller concrete crush scale). It should be noted that the additional available energy may also result in additional mass loss depending upon the calculation method the user switches on.
I assume no-one has issue with this mechanism.
I have added a switch to the new version of the model, allowing usage of the energy 'loss' through the conservation of momentum calculation to be used post impact, with one caveat:
The final velocity of the pile-driving mass cannot exceed the post impact velocity.
In situations where the calculated energy expenditure does not exceed the additional energy, the final velocity is limited to the post impact velocity, and the remaining energy assumed to be consumed by further material destruction (ie smaller concrete crush scale). It should be noted that the additional available energy may also result in additional mass loss depending upon the calculation method the user switches on.
I assume no-one has issue with this mechanism.
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What?
Are you a Hoffman concrete was all dust man?
Progression on; nothing stops 911Truth from making stupid conclusions, why would you not press on? So what conclusion are you trying to back-in this time?
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Numerous methods for crushing concrete exist in the model.
Post 877
It 'may' interest you to know the model version I am currently looking at uses an initial crush scale of 0.45cm for 50% of the concrete mass. (Impact KE related scaling). Hardly dust.
I also fail to see what conclusions I have made other than suggest that no-one has issue with the very sensible caveat mentioned. If you do have issue, I suggest you state what that issue is.
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Furcifer
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Great, you don't agree with Newtonian Mechanics. It might make progress difficult.
Perhaps it's late, but I can't make heads or tails of what modifications you have made. If the final velocity of the pile driving mass can't exceed the post impact velocity how will it ever increase velocity? On a floor by floor basis, isn't the final velocity the post impact velocity? Or are you assuming free fall every 3.6m?
This makes sense, oblique collisions will result in some of the deformed mass being ejected outside the perimeter. This mass will not contribute to the kinetic energy of the collapse. Assuming you have it set up right. I'm terrible with spreadsheets and how they function so I'll leave that to the professionals.
edit: looking at your spread sheet it says the next version will include the effects of drag. How? It's not like you are dropping a cube in air. Making a reasonable calculation of the drag looks very complicated at first glance. Just curious.
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Referencing the values used in this thread previously, I have added a switch, to enable usage of the 83.33e6 J for further use in the calculations performed on 'that' floor. These include overcoming the resisting steel structure, crushing concrete and debris ejection.
When switched on, the mechanism is also enabled for all subsequent floor impacts.
The post impact velocity value I refer to is just the post conservation of momentum calc velocity. The further factors are calculated afterwards as part of the per-floor mechanics. (You'll need to look at the spreadsheet for full clarity)
Subsequent velocity increase occurs through progression to the next floor, by free-fall of the resulting pile-driving mass (with appropriate initial velocity) over the floor height distance, until it impacts the 'next' floor.
(So, yes, free-fall every 'floor height'. Floor heights are specific. A constant floor height is not used.) Add: This is only in the new version. The one on my site does use constant floor height. Apologies.
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I think you are referring to the air resistance calc. It makes a very marginal collapse time difference, and will probably not be enabled. (If so, it will be a switch)
I should highlight that the mechanics do assume the dropping of a cube (well, flat surface with mass), as per all the crush down models, including the model outline by Ryan. The pile driving mass is treated as a single rigid body of mass (current version).
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Furcifer
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lol, I wish it did, I really need to learn excel. I was going to say the floor height looks constant to me, but then I noticed you added that it was.
Again, I'm not sure of what limitations your simulator has, but I'm curious if you can add the floor system as a seperate entity within the building. I saw a blurb that says you have yet to include the loss in deforming the floor system to the simulator. At some point the pancaking of the floors will become an issue. The way I see it, the floor system is a much lighter version of what you have with a hole cut out of the middle for the core, and detached from the exterior. It seems like a simple thing to do, but I'm not sure. Just a thought.
Furcifer
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Yes, the air resistance calc. It would probably be easier to estimate the mass of air per floor (plus suspended particulates or a percentage of the crushed concrete), the cross sectional area of the windows and a part of the core (as it would be partially filled with material but still an opening) and then consider it as a pump. You can subtract the pressure on the upper section due to the compression, plus you get a velocity of the air and ejected material.
This would actually work best with my earlier suggestion about treating the floors seperately. The only difference would be the core opening.
Anyways, just a few parameters to bounce off of you.
Collapse of the floor truss system will be included in a future version, yes.
I'll focus on the energy required to collapse a few key truss types, then replicating based on floor type.
I'll also be including a similar mechanism for the core floor systems (with of course the per-floor user specifiable core column percentage abilities to enable modeling of the partial core remnants). I may also look at stairwell and lift shaft implications.
Sounds reasonable to me, especially the inclusion of the window cross-sectional area.
There are of course limitations with how far I can go in spreadsheet form, which basically limits the mechanisms to a discreet number of 'steps' (currently floors).
The primary limitation is factors which incur asynchronous timing. (Simultaneous crush-down and crush-up is one such factor, as the timing of impact between floors then becomes asynchronous. I'm trying to find a way round this.)