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![[image loading]](http://i.imgur.com/ZN2NCwQ.png)
That's what the dutch website Nu.nl just posted. a brief translation:
Sources around the police told the Malaysian paper ''New Straits Times'' that Co-Pilot MH370 tried to call after it disappeared from radar.
He thinks Far Abdul Hamid's phone made contact with a transmission tower when the plane flew low, close to the Malaysian island Penang. But before the signal could be sent to the next transmission tower to have an actual phone call, the connection was lost.
Most likely because the plane flew away quickly and another tower couldn't be reached.
http://www.nu.nl/buitenland/3750180/co-piloot-mh-370-probeerde-nog-bellen.html
Nu.nl is a reliable source, sometimes a bit slow but always reliable. Seems this story isn't completely false.
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On April 12 2014 16:15 urboss wrote:
If they find it, is it going to be easy to salvage the wreck?
Can a crane on a ship lift 1000s of tons?
Typically they actually inflate giant airbags and float wreckages, not lift them with a crane.
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On April 12 2014 22:09 JerseyDevil wrote:
Typically they actually inflate giant airbags and float wreckages, not lift them with a crane.
Really? Maybe they do this in shallow waters.
I have my doubts that you can inflate an airbag of sufficient size at 5000m depth.
For the titanic they came up with all sorts of ideas, none of which seemed to work:
http://en.wikipedia.org/wiki/Wreck_of_the_RMS_Titanic
Admittedly the Titanic is 'slightly' heavier than a Boeing.
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On April 12 2014 16:45 urboss wrote:
wow, 20,000 tons should do it. Edit: I see, that is on land.
Mind that there is also the pressure of the water in 5000m depth the crane has to work against.
It's not too on-topic, but I can't stand seeing wrong physcis uncorrected  The pressure of water does not extert any force against lifting objects from it. On the contrary, the differential pressure (the higher the deeper you go) always provides upward force (the famous Archimedes law), almost (within the incompressibility of the water) regardless of the depth. The "only" problem the extreme pressure poses is in operating the machinery needed to fix any object to a rope to it, but it has no negative effect on the lifting proper. Anyway, I don't think it's reasonable to expect the plane to lie intact on the ocean floor, clear landing on water (free ocean water with high waves in particular) with a large jet is extremely rare, so the plane is likely broken into many scattered pieces.
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Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water?
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On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water?
nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere.
it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force!
Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part.
tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out.
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Thanks, I think I understand now.
The water pressure doesn't only act from above, but acts uniformly around the object.
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Hong Kong9153 Posts
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On April 13 2014 01:42 urboss wrote:
Thanks, I think I understand now.
The water pressure doesn't only act from above, but acts uniformly around the object.
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On April 13 2014 01:15 Hryul wrote:Show nested quote +On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water? nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere. it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force! Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part. tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out.
On April 13 2014 01:15 Hryul wrote:Show nested quote +On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water? nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere. it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force! Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part. tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out.
I find your explanation very misleading.
We don't get crushed by the air above us, because our internal cavities (lungs, etc.) match the pressure of the air surrounding us. The rest of us is more or less incompressible because we are mostly made from water and bone. The air does exert a force on us, but we are well matched to it for a lack of a better word.
The water column above an object exerts a force on the object. Actually the force is applied from all directions if the object is hollow. But again if the object is solid (incompressible) and also filled with water at the same pressure, it won't collapse because the pressure inside and outside is matched. An object filled with air at a different pressure than the water on the other hand will have considerable force exerted on it. That's why divers need to go up and down slowly in order for the pressure to equalize. Once there is a pressure differential, they risk that their lungs collapse (again simplified, there are also other problems).
All of this has little to do with Newton's second law. Archimides law is concerned with the buoyant force that an object experiences when submerged in a liquid and there is a density difference between the object and the liquid. So that's more concerned with how fast the object will rise, but not really about how much force is exerted on the object due to the pressure differential.
tldr: There is a force. Just blow up a balloon and submerge it in your filled bathtup if you don't believe me.
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On April 15 2014 02:23 Duka08 wrote:Show nested quote +On April 14 2014 17:15 BlueSpace wrote:On April 13 2014 01:15 Hryul wrote:On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water? nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere. it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force! Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part. tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out. On April 13 2014 01:15 Hryul wrote:On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water? nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere. it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force! Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part. tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out. I find your explanation very misleading. We don't get crushed by the air above us, because our internal cavities (lungs, etc.) match the pressure of the air surrounding us. The rest of us is more or less incompressible because we are mostly made from water and bone. The air does exert a force on us, but we are well matched to it for a lack of a better word. The water column above an object exerts a force on the object. Actually the force is applied from all directions if the object is hollow. But again if the object is solid (incompressible) and also filled with water at the same pressure, it won't collapse because the pressure inside and outside is matched. An object filled with air at a different pressure than the water on the other hand will have considerable force exerted on it. That's why divers need to go up and down slowly in order for the pressure to equalize. Once there is a pressure differential, they risk that their lungs collapse (again simplified, there are also other problems). All of this has little to do with Newton's second law. Archimides law is concerned with the buoyant force that an object experiences when submerged in a liquid and there is a density difference between the object and the liquid. So that's more concerned with how fast the object will rise, but not really about how much force is exerted on the object due to the pressure differential. tldr: There is a force. Just blow up a balloon and submerge it in your filled bathtup if you don't believe me. He's referring to the force required to move the object up or down, which the depth in the water doesn't affect. The force on an object due to a pressure differential is a separate topic.
In that case what he says would be wrong. There are two forces which are important in this case. The first is the gravitational force pulling the object downward to the bottom of the ocean and its buoyancy which will move the object upwards towards the surface.
The best way to understand buoyancy is by using pressure. The submerged object will experience a force from all sides. This force depends on the pressure, which becomes larger the deeper you move down towards the bottom of the ocean. Therefore the force at the bottom of the object differs from the force on top of the object which results in a net force that moves the object towards the surface.
That is the reason why the apparent weight of an object is smaller when submerged in water, which is what we experience every time we go swimming. For this explanation Newtown's third principle is completely irrelevant.
And also not to nitpick, but if the liquid involved is seawater, the object will change its buoyancy with depth because seawater isn't a perfect incompressible liquid. It actually has a higher density at lower depth because the seawater above it will exert force on it (It also changes with temperature and salinity, which further complicates things).
So the reason why in an ideal incompressible liquid (not seawater!) the force needed to move the object doesn't change with depth is because the density of the liquid doesn't change. The pressure changes with depth, but since we are not interested in the total pressure but the pressure differential between top and bottom of the object, the buoancy doesn't change with depth (unless the density changes with depth). And in any case the force pulling the object down is gravity which doesn't change that much with depth, because the plane is tiny compared to the earth.
tl;dr: Still wrong and don't use Newton's third principle here.
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On April 15 2014 15:52 BlueSpace wrote:Show nested quote +On April 15 2014 02:23 Duka08 wrote:On April 14 2014 17:15 BlueSpace wrote:On April 13 2014 01:15 Hryul wrote:On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water? nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere. it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force! Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part. tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out. On April 13 2014 01:15 Hryul wrote:On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water? nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere. it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force! Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part. tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out. I find your explanation very misleading. We don't get crushed by the air above us, because our internal cavities (lungs, etc.) match the pressure of the air surrounding us. The rest of us is more or less incompressible because we are mostly made from water and bone. The air does exert a force on us, but we are well matched to it for a lack of a better word. The water column above an object exerts a force on the object. Actually the force is applied from all directions if the object is hollow. But again if the object is solid (incompressible) and also filled with water at the same pressure, it won't collapse because the pressure inside and outside is matched. An object filled with air at a different pressure than the water on the other hand will have considerable force exerted on it. That's why divers need to go up and down slowly in order for the pressure to equalize. Once there is a pressure differential, they risk that their lungs collapse (again simplified, there are also other problems). All of this has little to do with Newton's second law. Archimides law is concerned with the buoyant force that an object experiences when submerged in a liquid and there is a density difference between the object and the liquid. So that's more concerned with how fast the object will rise, but not really about how much force is exerted on the object due to the pressure differential. tldr: There is a force. Just blow up a balloon and submerge it in your filled bathtup if you don't believe me. He's referring to the force required to move the object up or down, which the depth in the water doesn't affect. The force on an object due to a pressure differential is a separate topic. In that case what he says would be wrong. There are two forces which are important in this case. The first is the gravitational force pulling the object downward to the bottom of the ocean and its buoyancy which will move the object upwards towards the surface. The best way to understand buoyancy is by using pressure. The submerged object will experience a force from all sides. This force depends on the pressure, which becomes larger the deeper you move down towards the bottom of the ocean. Therefore the force at the bottom of the object differs from the force on top of the object which results in a net force that moves the object towards the surface. That is the reason why the apparent weight of an object is smaller when submerged in water, which is what we experience every time we go swimming. For this explanation Newtown's third principle is completely irrelevant. And also not to nitpick, but if the liquid involved is seawater, the object will change its buoyancy with depth because seawater isn't a perfect incompressible liquid. It actually has a higher density at lower depth because the seawater above it will exert force on it (It also changes with temperature and salinity, which further complicates things). So the reason why in an ideal incompressible liquid (not seawater!) the force needed to move the object doesn't change with depth is because the density of the liquid doesn't change. The pressure changes with depth, but since we are not interested in the total pressure but the pressure differential between top and bottom of the object, the buoancy doesn't change with depth (unless the density changes with depth). And in any case the force pulling the object down is gravity which doesn't change that much with depth, because the plane is tiny compared to the earth. tl;dr: Still wrong and don't use Newton's third principle here.
I use Newton's third principle whenever the fuck I want, because it is never wrong!
And on a more serious note: I might not have been as clear as I could have been, but I just wanted to demonstrate, that water pressure doesn't pose a problem for lifting an object once lifted from the ground of the sea. What I (wanted to) describe was the reason for buoyancy and I can't see where I was wrong there.
And to understand that you don't have to nitpick about compressibility of seawater, since you can neglect it locally.
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Seawater's density varies by water temperature, salinity, and depth. But once you get so deep it doesn't really change that much. Pressure would only matter with how it would interact with the flotation device as i would imagine the broken plane or parts would be open ans rhw pressure would either equalize quixkly or destroy the plane further.
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On April 15 2014 23:07 Hryul wrote:Show nested quote +On April 15 2014 15:52 BlueSpace wrote:On April 15 2014 02:23 Duka08 wrote:On April 14 2014 17:15 BlueSpace wrote:On April 13 2014 01:15 Hryul wrote:On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water? nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere. it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force! Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part. tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out. On April 13 2014 01:15 Hryul wrote:On April 13 2014 00:45 urboss wrote:
Thanks for the clarification.
I only have a vague memory of my physics classes.
I understand Archimedes law, but I don't understand why the water column above an object doesn't exert any force on it. Does this have something to do with some special features of water? nope. the same thing applies to air balloons or even just you, who doesn't get crushed by the tons of oxygen above you in the atmosphere. it's an application of Newton's law "action = reaction" (Kraft = Gegenkraft). let's assume the plane is "in the water", so not grounded yet. so intuitively, there is the water pushing down the plane. (academic note: so then the plane pushes against the water to the top, but that's not important). Then there is the plane pushing on the water underneath it. but since action = reaction, the water pushes back with the exact same amount of force! Now for an object to move there must be a "net force" in a direction. so we add both forces from the water to the plane and what we see (math is on wiki), is that the forces from the water pushing from the top and the bottom cancel out except for a part containing the height difference between top and bottom part. tldr: it does exert force, but due to newton's law "action = reaction" most of it cancels out. I find your explanation very misleading. We don't get crushed by the air above us, because our internal cavities (lungs, etc.) match the pressure of the air surrounding us. The rest of us is more or less incompressible because we are mostly made from water and bone. The air does exert a force on us, but we are well matched to it for a lack of a better word. The water column above an object exerts a force on the object. Actually the force is applied from all directions if the object is hollow. But again if the object is solid (incompressible) and also filled with water at the same pressure, it won't collapse because the pressure inside and outside is matched. An object filled with air at a different pressure than the water on the other hand will have considerable force exerted on it. That's why divers need to go up and down slowly in order for the pressure to equalize. Once there is a pressure differential, they risk that their lungs collapse (again simplified, there are also other problems). All of this has little to do with Newton's second law. Archimides law is concerned with the buoyant force that an object experiences when submerged in a liquid and there is a density difference between the object and the liquid. So that's more concerned with how fast the object will rise, but not really about how much force is exerted on the object due to the pressure differential. tldr: There is a force. Just blow up a balloon and submerge it in your filled bathtup if you don't believe me. He's referring to the force required to move the object up or down, which the depth in the water doesn't affect. The force on an object due to a pressure differential is a separate topic. In that case what he says would be wrong. There are two forces which are important in this case. The first is the gravitational force pulling the object downward to the bottom of the ocean and its buoyancy which will move the object upwards towards the surface. The best way to understand buoyancy is by using pressure. The submerged object will experience a force from all sides. This force depends on the pressure, which becomes larger the deeper you move down towards the bottom of the ocean. Therefore the force at the bottom of the object differs from the force on top of the object which results in a net force that moves the object towards the surface. That is the reason why the apparent weight of an object is smaller when submerged in water, which is what we experience every time we go swimming. For this explanation Newtown's third principle is completely irrelevant. And also not to nitpick, but if the liquid involved is seawater, the object will change its buoyancy with depth because seawater isn't a perfect incompressible liquid. It actually has a higher density at lower depth because the seawater above it will exert force on it (It also changes with temperature and salinity, which further complicates things). So the reason why in an ideal incompressible liquid (not seawater!) the force needed to move the object doesn't change with depth is because the density of the liquid doesn't change. The pressure changes with depth, but since we are not interested in the total pressure but the pressure differential between top and bottom of the object, the buoancy doesn't change with depth (unless the density changes with depth). And in any case the force pulling the object down is gravity which doesn't change that much with depth, because the plane is tiny compared to the earth. tl;dr: Still wrong and don't use Newton's third principle here. I use Newton's third principle whenever the fuck I want, because it is never wrong! And on a more serious note: I might not have been as clear as I could have been, but I just wanted to demonstrate, that water pressure doesn't pose a problem for lifting an object once lifted from the ground of the sea. What I (wanted to) describe was the reason for buoyancy and I can't see where I was wrong there. And to understand that you don't have to nitpick about compressibility of seawater, since you can neglect it locally.
It is actually very simple. You said that there is water pushing from the top and this causes a counterforce. And that the plane pushes against the water underneath it causing another counterforce. And that those cancel each other out.
Actually it's the same water above the plane that pushes from the top as well as from the bottom at the same time. There is just more water above the plane seen from the bottom, then seen from the top. And this is what causes a force pushing the plane up. Now the force with which the plane is pushing downward is actually caused by the gravity field of the earth which is something else.
You can use Newton's third now and tell me that the plane is also pulling the earth towards it at the same time 
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Actually it's the same water above the plane that pushes from the top as well as from the bottom at the same time.
Dude, your explanations aren't simple, but quite confusing 
But I guess you were right: It's not the gravitational force of the (mass of the) plane but the difference in pressure of the water which causes buoyancy.
This pressure difference is also caused by the gravity field of the earth. So it's not completely unrelated
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Buoyancy is basically the weight of the water displaced so, and weight of water displaced is found by the volume of the object. An object displaces water equal to its volume, volume of water * density of water= mass displaced, mass displaced * force of gravity = Newtons of force
Since gravity is acting on both the water and the object when the mass of the object and the mass of water displaced are the same the buoyancy force is equal to the objects weight and it reaches equilibrium.
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The probe Bluefin-21 has finished searching 90% of the area without finding anything.
Poll: I believe that...The plane crashed in a different part of the ocean. (6) 46% The search area NW of Perth is correct. (5) 38% The plane has landed on solid ground. (2) 15% 13 total votes Your vote: I believe that... (Vote): The search area NW of Perth is correct.
(Vote): The plane crashed in a different part of the ocean.
(Vote): The plane has landed on solid ground.
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This poll is dumber than CNN reading twitter reactions as news.
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On April 25 2014 16:57 urboss wrote:The probe Bluefin-21 has finished searching 90% of the area without finding anything. Poll: I believe that...The plane crashed in a different part of the ocean. (6) 46% The search area NW of Perth is correct. (5) 38% The plane has landed on solid ground. (2) 15% 13 total votes Your vote: I believe that... (Vote): The search area NW of Perth is correct.
(Vote): The plane crashed in a different part of the ocean.
(Vote): The plane has landed on solid ground.
This is my story and I'm sticking to it...
HANNITY: General, I've known you a long time. I know you too well to know that you're not just making this up, this isn't something you've concocted. You've spoken to a number of people, am I correct?
MCINERNEY: Yes, but that's all I want to say, Sean, please.
HANNITY: Fair enough. And you believe this plane is intact and that this plane landed?
MCINERNEY: I do.
http://nation.foxnews.com/2014/03/19/could-missing-plane-be-held-pakistan
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EPT
