Well Huntsman if you have two trains, one carrying the upper block (say N floors) and another train carrying the remainder of the wtc (say M-N) and they collide, what will happen ?
And this is exactly why I call you ignorant. ANd moreso, an arrogant idiot for insisting your ignorance is knowledge.
the train carrying the rest of the wtc can be thought of as another block of N floors plus a block of M-2N floors.
No, it can't.
Do you think that when a collision takes place the N floors stay intact during the whole collision through the other massive block ?
Strawman. You are the only one who has argued this, because you're an idiot.
In fact it is a stepwise collision floor by floor. Whether you use Greening or not, it will not really affect the collapse time, that is also not important. What is important that there is symmetry in the situation; it is in fact two trains colliding with 4.3 m/s, the block of N floors will be destroyed in the same rate as the floors on which it collides (or falls).
I'll take this, more or less, as accurate.
The speed after a stepwise collision of N floors will not really be different (it will be slowed down by conservation of momentum but increase by gravity, it is no closed system, I think that is a nice problem to solve in the future), but then what is left then ? If you look again at the movie and mass falls away during the process, mass is conserved, but it goes in all directories then the question is what the initial momentum is to break the next floor ? It is plausible that we can again use the mass of the initial block?
And again, I say you are ignorant, arrogant, and an idiot.
I agree that the floors of the upper block will be destroyed just like the floor they are falling on.
So what? What does this mean?
You seem to believe that this means their mass disappears. You seem to think that destroyed means disintigrated. You seem to think that a simple fall violates one of the foundation of the science of physics, namely conservation of mass-energy. You are an ignorant ********* who speaks from his fourth point of contact.
Whetehr the upper portion is one block, or a formless mass of rublle, it still has more than enough weight to crush any floor it lands on. Now, let's take it further, since I have to explain this to you as if you were an eight yerar old, which seems to be about your level of understanding.
Assume a building with 100 floors (for simplicity).
The top ten floors (upper block, UB) have a weight of 10x. The bottem 90 (bottem block, BB) have a mass of 90x.
The UB impacts and destoys the top floor of the BB. This also destroys the bottem floor of the UB. Let's say that a mass equal to an entire floor is thrown outward from this impact.
So what is the amount of mass left to fall?
10x is your initial. THe impact throws out an entire floor's worth of mass, leaving 9x. However, the top floor of BB is destroyed, and is now falling as well, so adds to the UB. So, the mass of the UB is 10x.
And entire floor's worth of mass can be thrown out at each step along the fall, and the mass of the falling matter is still 10x. Every time. Doesn't matter if it's an intact block or not (unless you are ignorant of physics and don't understand what you're talking about, yet somehow still beleive you're more qualified than experts. If you ever had a physics degree I'm a f*&king brain surgeon, liar). And this leaves ONLY 10 floor's weight of mass in the footprint.
There is more to add, Greening assumes a uniform mass distribution, but the building will be stronger at the bottom than at the top. This will slow down the fall, this will disintegrate the block in a higher rate, this will increase the collapse time.
Except that by the time it gets to the lower floors, it will be a heavier mass falling, so it won't really matter. Unless you really want to argue that only 10% of the mass was left in the footprint at the bottem?
Didn't think so, idiot.
Also the fact that at one tower the block falls skew is not a trivial calculation. Isn’t video material important? Of course, that is all that is available about it.
Not really. It falls with a MUCH higher doward velocity than side, and as you said the block was destoryed in the fall anyway, so those bits of matter continue downard. Idiot.
There is even more to add,
I do hope anythign else is actually sensible and shows some type of knowledge, rather than being pulled out of your anus to try and impress people with your idiocy.
point masses are of course relevant for a first approximation, but in this case it affects the collapse time very much. Because if you assume point masses (in fact in a 2d area) then during the whole length of two floors there is free fall assumed which means that the momentum will increase during those 3.7meter. The next collision will decrease it (because of the bigger mass) but then it has again 3.7meter to increase its momentum and so on. All stuff between the floors including the steel core etc is assumed to break by loss of kinetic energy. If you do that allright, but since the real situation is not a point mass situation some time should be added.
How much does a fly slow down your car when it hits the windshield?
Or even better, how much does a small car slow when it hits a large dog?
Idiot.
The problem I personally have is the initial fall; it’s hard for me to accept this.
So where's your math? Or are we accepting fallacious Arguments from Incredulity now? It's not true because you don't think so? Try again, idiot.
Further Greening’s model gets no terminal velocity and that is not a realistic physical model, it goes to infinity if there are enough floors.
It's an approximation. Doesn't matter. There were nowhere near enough floors to reach that speed. You might as well argue against figuring any acceleration due to gravity, because it doesn't include terminal velocity either.
Idiot.
It would be nice if Mr. Greening does a similar calculation for a less mathematical and more physical model, he would be the best one to do that, I’m convinced.
Well, it might help convince him if you had any actual criticisms based on realistic objections.
Idiot.
I've never seen the term "perfectly inelastic" before, but perhaps my professors were simply more precise. From now on, whenever I see "perfectly inelastic" or "totally" or "fully" or whatever, I will assume we are referring to a collision in which the end state has the two bodies in contact or fused together.
