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Heiwa's Pizza Box Experiment

By the way, repeating the 'treason to question the government' lie over and over doesn't help your case, it makes you look stupid.
 
phunk said:
Good god Heiwa, you are completely lost.

Let me repeat. For friction to stop the top of the tower, it has to create a force F that's much greater than mg, that is enough to decelerate the top of the tower to 0. That entire force F must be supported by the columns, unless you're postulating that the floors could magically levitate. Bazant showed that the momentum of the moving upper block was too much for the columns to support. It's really that simple.
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Well, the ball with mass m bounced and that's evidence that collapses can be arrested ... by gravity and friction. Bazant assumes the ball (upper block) to be rigid and the ground (columns) soft and there is no friction and only movement down, 1-D, is permitted, and all energy involved is instantaneoulsy applied to the soft colums (upper block remains intact all the time) but that's not so, of course. That's really stupid assumptions.

NIST is worse! Lack of capabilty of strain energy of lower structure to absorb kinetic energy applied?!? Well, the lower structure can absorb and deflect much more energy than its built in strain energy when local failures occur. NIST also ignores that friction is not just built in strain energy. And the kinetic energy must of course be applied to the structure. Not so easy! It slips off. Try to use force to remove a rusty bolt and the tool may get damaged and slip off. Further destruction (removal of rusty bolt) is arrested.

It is not the forces alone that arrest the collapse. It is the energy consumed, when these forces displace in various ways and directions and cause local failures to occur, that causes the arrest. Not to forget energy just slipping off the structure you try to destroy.

A rusty bolt very often damages the tool used to remove it. Or only the head of the rusty bolt gets damaged and then the tool cannot grip the bolt any more. It is not easy to apply force/energy to a structure.

Pls use laymen's terms in your posts ... and it will be easier to understand what you try to communicate. And no differential equations based on misty assumptions.

PS - The purpose of the Pizza Box Tower experiment was just to illustrate that upper blocks, impactors that are supposed to destroy towers, are not rigid, etc. Very popular experiment - combined with a pizza party. + plenty of red wine, of course.
 
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Heiwa, do you believe that the columns could stand by themselves with all the floors removed?
 
[X] said:
Let's run through this again:

Now let's re-phrase it slightly:

There is a 1 kilogram mass on a frictionless plane. A 1 Newton force is applied to this mass, and is not removed. After 1 second, the mass has reached a plane that has friction. The force of kinetic friction is equal to exactly 1 Newton (coefficient of friction is therefore equal to 1/mg).

What is the direction, velocity and acceleration of the mass at time > 1 second?
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OK, let's do it in laymen's terms. A ship with mass 1 kg is pushed forward by a force of 1 N (the turning propeller provides this force/thrust) and accelerates it at a = 1 m/s² because a = F/m in the water (resistance ignored). However, the water at a certain speed of the ship (say the speed achieved after 1 second) provides a resistance force of 1 N in the opposite direction, so the ship does not accelerate any more and continues at constant speed through the water. Happy cruising! The ship is crushing the water while cruising. But energy is required - for every meter the ship moves forward, 1 Nm of energy is consumed because that's what is needed to move it 1 meter. Note that the mass of the ship is irrelevant then.

If you turn off the propeller, the ship comes to a halt as only the resistance force is then acting on the mass. The resistance force is however a function of the speed so it takes a while for it to stop the vessel.

But you are not turning off the propeller. You are happy crusing on and do not see the big ice berg floating in your way.

The ship impacts the ice berg with force 1 N which produces a big BANG. The ice berg does not like that and applies a force 1 N on the ship's bow that is crushed, because it was not very rigid. Of course the ice berg is also damaged a little by the ship, but it knows about Newton's third law, so it fights back.

So what happens then? Well the ship and you are arrested! End of cruise. The ship does not slice through the ice berg at constant speed if you ever thought that.

Imaging what a force of 1 N can do!
 
Smackety said:
Heiwa, do you believe that the columns could stand by themselves with all the floors removed?
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Yes! All the weights transmitted to the columns by the floors are then removed. And as the columns are supported horizontally by spandrels and beams, there are no problems. It would look like a big bird cage. Read my papers.
 
phunk said:
By the way, repeating the 'treason to question the government' lie over and over doesn't help your case, it makes you look stupid.
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Treason is a crime. Infidelity in marriage is not a crime. We are just discussing the Pizza Box Tower experiment and it is fun.
 
Is Heiwa for real?

This has to be a mickey take. nobody, I mean NOBODY can take him seriously. What he personally gets out of winding everyone up God alone knows, but it's just plain boring, and a bit sad.

Bananaman.
 
Heiwa said:
A ship with mass 1 kg is pushed forward by a force of 1 N (the turning propeller provides this force/thrust) and accelerates it at a = 1 m/s² because a = F/m in the water (resistance ignored). However, the water at a certain speed of the ship (say the speed achieved after 1 second) provides a resistance force of 1 N in the opposite direction, so the ship does not accelerate any more and continues at constant speed through the water.
Click to expand...

So far you are correct.

Heiwa said:
The ship impacts the ice berg with force 1 N which produces a big BANG. The ice berg does not like that and applies a force 1 N on the ship's bow that is crushed, because it was not very rigid. Of course the ice berg is also damaged a little by the ship, but it knows about Newton's third law, so it fights back.

So what happens then? Well the ship and you are arrested! End of cruise. The ship does not slice through the ice berg at constant speed if you ever thought that.

Imaging what a force of 1 N can do!
Click to expand...

The iceberg cannot stop the ship by itself if it only applies a force of 1N. Since the propeller is providing 1N, to stop the ship will require a force in the opposite direction of greater than 1N. If you include the 1N from the iceberg and the 1N from water resistance, from your example, the ship will eventually be stopped. Although since your 1N of water resistance requires the ship to be moving at a particular speed, this resistance will decrease as the ships speed decreases, which would mean that the ship takes a nearly infinite amount of time to reach a full stop. But as we keep telling you, stopping the ship requires a force GREATER than the one already present in the opposite direction.

To equate to the towers...to arrest the collapse, the sum of the forces acting against gravity must be greater than the force of gravity to arrest the collapse.

ETA: Italics
 
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Heiwa said:
Yes! All the weights transmitted to the columns by the floors are then removed. And as the columns are supported horizontally by spandrels and beams, there are no problems. It would look like a big bird cage. Read my papers.
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Wrong, the floors were part of the support system for the columns, they weren't given enough horizontal support to stand on their own without the floors.
 
Heiwa said:
OK, let's do it in laymen's terms. A ship with mass 1 kg is pushed forward by a force of 1 N (the turning propeller provides this force/thrust) and accelerates it at a = 1 m/s² because a = F/m in the water (resistance ignored). However, the water at a certain speed of the ship (say the speed achieved after 1 second) provides a resistance force of 1 N in the opposite direction, so the ship does not accelerate any more and continues at constant speed through the water. Happy cruising! The ship is crushing the water while cruising. But energy is required - for every meter the ship moves forward, 1 Nm of energy is consumed because that's what is needed to move it 1 meter. Note that the mass of the ship is irrelevant then.
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Correct. When the accelerating force is equal to the resisting force, no acceleration takes place and the object moves at a constant velocity.

Really, that's all that need be said.

You have confirmed, yet again, that if the resistance provided by the towers (F1 is equal to M1g, then the falling mass will continue to move at a constant velocity.

Hence, in order for the collapse to arrest, the resistance force must be greater than M1g.



Heiwa said:
If you turn off the propeller, the ship comes to a halt as only the resistance force is then acting on the mass. The resistance force is however a function of the speed so it takes a while for it to stop the vessel.
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Correct. Why does it stop? Because the resistance force is greater than the propelling force!

You have confirmed, yet again, that if the resistance provided by the towers (F1 is greater than M1g, then the falling mass will decelerate (slow down) during its descent.

Hence, in order for the collapse to arrest, the resistance force must be greater than M1g.



Heiwa said:
But you are not turning off the propeller. You are happy cruising on and do not see the big ice berg floating in your way.

The ship impacts the ice berg with force 1 N which produces a big BANG. The ice berg does not like that and applies a force 1 N on the ship's bow that is crushed, because it was not very rigid. Of course the ice berg is also damaged a little by the ship, but it knows about Newton's third law, so it fights back.

So what happens then? Well the ship and you are arrested! End of cruise. The ship does not slice through the ice berg at constant speed if you ever thought that.

Imaging what a force of 1 N can do!
Click to expand...


If the ship is cruising happily along (I assume that the 1 Newton propulsive force is balanced by the 1 Newton of resistance force) and then hits an iceberg which provides 1 Newton of resistance, you now have 2 Newtons of force resisting the 1 Newton propulsive force.

The net force is -1 Newton (i.e. backwards to direction of ship movement), decelerating the ship.

It's that imbalance of forces that makes the ship slow down and stop.

You have confirmed, yet again, that if the resistance provided by the towers (F1 is greater than M1g, then the falling mass will decelerate (slow down) during its descent.

Hence, in order for the collapse to arrest, the resistance force must be greater than M1g.



But that is not what you are saying in regards to the towers!

You state that the towers can only provide a resistance equal to M1g.

And since that is the only resistance on the upper section (of which the propulsive force is also equal to M1g), then there is no net force and the upper section continues to move downwards at a constant velocity.

Remember, Heiwa, this is not what I'm saying should happen, this is what is predicted by your model.

When you say the resistance cannot be larger than M1g, simple physics gives this as the result.



Do you see now that it is wrong to claim that F1 = M1g will cause the tower collapse t halt? Do you understand why Dave Rogers, myself,and others have been telling you that in order for the collapse to halt, you have to have F1 > M1g? Probably not. You are fine when doing the examples, but somehow when talking about the towers, it as if the laws of physics that you've agreed apply to every example so far suddenly are different. I'm starting think that you know your claim was in error, and are protesting the point merely to avoid admitting it, and apologizing to Dave Rogers. Which is dishonest. Indeed, it would mean you've been lying every single time you've claimed F1 = M1g would low the collapse. One last try, Heiwa: Admit you were wrong, and fix your model. Or continue to wonder why no one on this board takes you seriously. (Hint: read through the last several ages of this thread to understand why.)
 
nicepants said:
The iceberg cannot stop the ship by itself if it only applies a force of 1N. Since the propeller is providing 1N, to stop the ship will require a force in the opposite direction of greater than 1N. If you include the 1N from the iceberg and the 1N from water resistance, from your example, the ship will eventually be stopped. Although since your 1N of water resistance requires the ship to be moving at a particular speed, this resistance will decrease as the ships speed decreases, which would mean that the ship takes a nearly infinite amount of time to reach a full stop. But as we keep telling you, stopping the ship requires a force GREATER than the one already present in the opposite direction.

To equate to the towers...to arrest the collapse, the sum of the forces acting against gravity must be greater than the force of gravity to arrest the collapse.

ETA: Italics
Click to expand...

Let's take it again in laymen's terms. Ship is pushed by propeller force 1 N at certain speed x and is subject to resistance force -1 N at that speed x. There is balance of forces and you cruise at constant speed x. No acceleration. For every meter you cruise the energy required is 1 Nm.

Now you hit an ice berg and let's assume that the ship stops at once (rapid deceleration to x = 0), but is still pushed forward by the propeller force 1 N. As there is no velocity any more, there is no water resistance; reason why the ship does not move any longer is that the ice berg applies force -1 N on the ship.

There is again balance of forces, etc. But you do not move. But energy is still required to push the ship with 1 N against the ice berg. If you look aft you will now see the propeller pushing a lot of water aft - that's where the energy goes to produce 1 N!

Anyway - back to the ice berg at the other end. Before the impact with the ice berg propeller force 1 N was nicely balanced by water resistance force -1 N and you happily cruised at speed x. The propeller was designed to produce this thrust/force 1 N = no problems there. The water resistance force -1 N was applied to the complete wet surface of the ship = no problems there. Big surface! Some paint may be polished off.

But when you hit the ice berg, BANG, and the velocity suddenly becomes 0 (very rapid deceleration and anything loose on the ship will proceed with speed x forward), the propeller pushes the ship against it with force 1 N, the ice berg applies the force - 1 N only to the shaped bow of the ship. And that bow was not designed to resist a point load of -1 N. Local stresses in the structure will become very high. But the total force is still only - 1N.

Please - you must realise that the force cannot be bigger than -1 N! But it is sufficient to stop the ship and cause havock.

Thus the bow is damaged, CRUNCH! (Evidently also the ice berg is deformed a little, but who cares about an ice berg?)

But you could be lucky! Say the ship's bow was made extra strong to resist a collision with an ice berg, i.e. to resist force -1 N applied to the bow; then you may bounce off the ice berg and go off in another direction. Or stop.

Or, do you just slice through the iceberg using your propeller force 1 N and continue at constant speed and no deceleration at impact, etc? This is unlikely in reality, but this is what Bazant wants you believe in his NWO ivory tower. For this strange event to take place Bazant assumes that the ship suddenly becomes rigid and applies a shock wave into the ice berg so it collapses into snow flakes ... and the ship proceeds as if nothing had happened (just the water still providing resistance as usual).

But believe me - the ice berg will stop the ship. The Bazant shock wave will not produce snow flakes. You need plenty of energy to crush an ice berg into snow flakes and it is not available at the impact. Same applies when the WTC1 top collides with the lower structure.

BTW - it does not take infinite time to stop a ship, if you shut off the propeller force 1N at speed x. The ship will just decelerate at a certain rate, while the kinetic energy available when you shut of the propeller - mx²/2 Nm - is absorbed by the water resistance/friction (a function of speed at any time during deceleration). When the kinetic energy is consumed, ship stops. Just try it yourself in any boat. If you impact an ice berg or a jetty, you will be stopped much quicker though.
 
phunk said:
Wrong, the floors were part of the support system for the columns, they weren't given enough horizontal support to stand on their own without the floors.
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Wrong, when you remove the floors you also remove the loads transmitted to the columns and the stresses in the columns will become very small ... and they will stand up like flag poles.
 
phunk said:
And questioning the government isn't treason, and treason has nothing to do with this discussion, so stop saying it.
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Sorry, questioning the government at war is treason in the US and US is at war. Homeland security will ensure that you are silenced. But I agree, it should be the topic of another thread.
 
[X] said:
If the ship is cruising happily along (I assume that the 1 Newton propulsive force is balanced by the 1 Newton of resistance force) and then hits an iceberg which provides 1 Newton of resistance, you now have 2 Newtons of force resisting the 1 Newton propulsive force.
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Pls refer to my previous post. Evidently there is no water resistance -1 N after impact, etc. That's where you go wrong.
 
Heiwa said:
Wrong, when you remove the floors you also remove the loads transmitted to the columns and the stresses in the columns will become very small ... and they will stand up like flag poles.
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Wrong. Wrong. Wrong. How many 110 story flag poles have you ever seen freestanding?

In real life, I mean.
 
Heiwa said:
But when you hit the ice berg, BANG, and the velocity suddenly becomes 0 (very rapid deceleration and anything loose on the ship will proceed with speed x forward),
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You're taking the most important part of the thought experiment and reducing it to 'BANG'. Hilarious.

It's that sudden deceleration that is the very crux of the argument. The force on the ship and the iceberg during that brief deceleration is way, way more than 1N. In fact the force is inversely proportional to the deceleration time. When you propose instant decelertation to 0, you're proposing infinite force.
 
phunk said:
You're taking the most important part of the thought experiment and reducing it to 'BANG'. Hilarious.

It's that sudden deceleration that is the very crux of the argument. The force on the ship and the iceberg during that brief deceleration is way, way more than 1N. In fact the force is inversely proportional to the deceleration time. When you propose instant decelertation to 0, you're proposing infinite force.
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Which, last time I checked, is a bit larger than 1...
F=m(V2-V1)/(T2-T1) where V2=final velocity, V1=initial velocity, T2-T1 is the time it takes to go from V1 to V2
 
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