Newton's third law of motion. Is it true? Is it still held true today?



08072013, 01:46 PM




RE: Newton's third law of motion. Is it true? Is it still held true today?
(08072013 01:34 PM)TheBeardedDude Wrote:(08072013 01:28 PM)Phaedrus Wrote: According to I and I's laws of physics, if you fired a bullet into a car door you should expect to find chunks and pieces of the bullet *in front of* the car door. Yeah...I've heard people say that 9/11 couldn't have happened because the wings of those planes would have sheared off when they hit the buildings. But...this is not the case. Jetliners wings are designed and tested to withstand 4gs  even thought the airframes are rated to about 2.5 G's max. So, given that a fullyloaded and fueled Boeing 767 weighs about 400,000 pounds, the max load that can be put on those wings without breaking is 1.6 Million Pounds (800 tons). That means that these wings are built tough  really tough  and are not going to break easily since they have to last for 20 years or more while being loaded with up to 400,000 pounds for 8+ hours per day. 

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08072013, 01:49 PM




RE: Newton's third law of motion. Is it true? Is it still held true today?
(08072013 01:46 PM)Julius Wrote:(08072013 01:34 PM)TheBeardedDude Wrote: Or, if you throw a baseball through a window, then pieces of the baseball should be thrown backwards towards the pitcher. Not only that it wasn't like the side of the skyscraper was made of concrete, it was mostly glass that plane punched through and only hit reinforced steel once it was actually inside the outer facade. 

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08072013, 02:19 PM




RE: Newton's third law of motion. Is it true? Is it still held true today?
(08072013 01:28 PM)Phaedrus Wrote: According to I and I's laws of physics, if you fired a bullet into a car door you should expect to find chunks and pieces of the bullet *in front of* the car door. (08072013 01:34 PM)TheBeardedDude Wrote: Or, if you throw a baseball through a window, then pieces of the baseball should be thrown backwards towards the pitcher. (08072013 01:46 PM)Julius Wrote: Yeah...I've heard people say that 9/11 couldn't have happened because the wings of those planes would have sheared off when they hit the buildings. But...this is not the case. Jetliners wings are designed and tested to withstand 4gs  even thought the airframes are rated to about 2.5 G's max. So, given that a fullyloaded and fueled Boeing 767 weighs about 400,000 pounds, the max load that can be put on those wings without breaking is 1.6 Million Pounds (800 tons). That means that these wings are built tough  really tough  and are not going to break easily since they have to last for 20 years or more while being loaded with up to 400,000 pounds for 8+ hours per day. (08072013 01:49 PM)Revenant77x Wrote: Not only that it wasn't like the side of the skyscraper was made of concrete, it was mostly glass that plane punched through and only hit reinforced steel once it was actually inside the outer facade. Facts are meaningless. You can use facts to prove anything that's even remotely true. Facts, schmacts. ... this is my signature! 

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09072013, 01:03 PM




RE: Newton's third law of motion. Is it true? Is it still held true today?
Newton's third law is really the conservation of momentum, which is really an expression about the symmetry of the Lagrangian under a spatial translation, a consequence of the fact that the laws of physics do not depend on position. Technically, there are two types of momenta, the ordinary momentum you will see in a high school textbook, p = mv, and there is the conjugate momentum, p = ∂L/∂v, where L is the Lagrangian, v is the velocity, and ∂ means partial derivative. These two are not necessarily the same. In quantum mechanics, the momentum and position are incompatible observables, meaning, if you measure one precisely, the other is indeterminate. This is a consequence of the Heisenberg Uncertainty Principle.
In inelastic collisions, a good part of the kinetic energy(KE) is transformed into heat, sound and molecular energy (deformation/breaking up of the colliding objects). Now since KE = p^2/2m, a lost in KE of the colliding objects will mean a loss in p for the colliding objects. But the total energy is conserved, so the total momentum is therefore also conserved. So part of the momentum lost by the colliding bodies is carried by the air molecules, the sharpnels and sound waves. 

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09072013, 01:05 PM




RE: Newton's third law of motion. Is it true? Is it still held true today?
(09072013 01:03 PM)zaybu Wrote: Newton's third law is really the conservation of momentum, which is really an expression about the symmetry of the Lagrangian under a spatial translation, a consequence of the fact that the laws of physics do not depend on position. Technically, there are two types of momenta, the ordinary momentum you will see in a high school textbook, p = mv, and there is the conjugate momentum, p = ∂L/∂v, where L is the Lagrangian, v is the velocity, and ∂ means partial derivative. These two are not necessarily the same. In quantum mechanics, the momentum and position are incompatible observables, meaning, if you measure one precisely, the other is indeterminate. This is a consequence of the Heisenberg Uncertainty Principle. The translation for I & I goes something like this: HAAHAHAHAAAHAHAHA!!! What a fucking moronic notion that you have. HAHAHAHAHA! “Science is simply common sense at its best, that is, rigidly accurate in observation, and merciless to fallacy in logic.” —Thomas Henry Huxley 

09072013, 05:12 PM




RE: Newton's third law of motion. Is it true? Is it still held true today?
(09072013 01:05 PM)TheBeardedDude Wrote:(09072013 01:03 PM)zaybu Wrote: Newton's third law is really the conservation of momentum, which is really an expression about the symmetry of the Lagrangian under a spatial translation, a consequence of the fact that the laws of physics do not depend on position. Technically, there are two types of momenta, the ordinary momentum you will see in a high school textbook, p = mv, and there is the conjugate momentum, p = ∂L/∂v, where L is the Lagrangian, v is the velocity, and ∂ means partial derivative. These two are not necessarily the same. In quantum mechanics, the momentum and position are incompatible observables, meaning, if you measure one precisely, the other is indeterminate. This is a consequence of the Heisenberg Uncertainty Principle. If I & I can understand any of my blogs at http://soi.blogspot.ca/ I'll certify him a PhD. ;) 

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09072013, 05:56 PM




RE: Newton's third law of motion. Is it true? Is it still held true today?


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