| | |||||||
| Register | Search | Today's Posts | Mark Forums Read |
| Physics Forum Physics Forum. Discuss and ask physics questions, kinematics and other physics problems. |
| | LinkBack | Thread Tools | Display Modes |
|
#1
| |||
| |||
| > This is directly implied by Newton's First Law, which does away with Absolute velocity does not disallow equivalent intertial reference frames. Furthermore, Newton's first law is WRONG. To say that bodies have default linear motion is in total contradiction with observation. Not to mention the fact that Newtons third law is a logical fallacy. A forces opposing force cannot be itself and it cannot be not itself. Otherwise the notion of cause is totally lost or the cause ends up creating an infinity of separate opposing forces of equal magnitude which would make no sense either. Speed of light has been observed to vary. So transistively, relativity is wrong. Maxwell got it wrong. Delbruck scattering is well known and even a 12 year old can infer that for a particle to move in a discontinuous path then it must have changed velocity magnitude at that point. I can confirm anything when all discrepencies in theory result in the "discovery" of fantastical new entities (i.e. dark matter). |
|
#2
| |||
| |||
| [Only registered users see links. ] (John Schoenfeld) writes: In which there are quantities like friction. It is virtually impossible to observe motion on the Earth in the complete absence of force. Newton's Third Law is the statement that all forces can be paired in such a manner that each force in a pair is a reaction to the other. If F2 is the counter-force to F1, then F1 and F2 make up one of these pairs, and so the counter-force to F2 is the other force in the pair, i.e. F1. This means that Newton's Third Law does apply: it is just the guarantee that every force can be paired with another force. F1's mate in its pair is F2. F2's mate in its pair is F1. The concept that counter-force is caused by acceleration is wrong. The fact is that Newton's Third Law tells us that forces always come in pairs. If the "counter-force" had been caused by acceleration alone, then what accounts for that a body which experiences a number of different forces simultaneously also exerts a number of forces simultaneously? They can't all be caused by acceleration. If all the forces on a body balance, then the body undergoes no acceleration but it still exerts a reaction to each force on it. Since the body is not accelerating in that case, then it has no acceleration which can be used to cause these "counter-forces", and yet it still manages to exert the "counter-forces". In short, the interpretation that the counter-force is caused by acceleration is wrong. Instead, forces are caused in such a manner that both action and reaction come into being simultaneously and are caused by the same mechanism, not by each other. And as a reminder, if the force F1 is exerted on the body B by the body A, then the paired force F2 is exerted on the body A by the body B. That is, for each pair of forces, the body experiencing one of the forces is exerting the other, and vice versa. That is true if you make the wrong interpretation that reaction is caused by acceleration (an interpretation which is untenable as shown above). If you make the interpretation that both an action and its reaction are caused by the same mechanism, then there is no logical problem. So now we have the situation where any mechanical mechanism casues forces in pairs, and the forces in a pair are equal in magnitude and opposite in direction. The mechanism causes both forces, and neither force causes the other. <snip> This from the person who claimed that Maxwell only introduced the displacement current term into the equation for curl H in order to make the equations more symmetric, rather than in order to make the equations consistent with conservation of charge, which was the real reason why the displacement current term was introduced, i.e. to make the theory mathematically consistent. Without the displacement current term, the theory was inconsistent (the equations could not hold simultaneously with conservation of charge), so the term was necessary for consistency. <snip other attacks on the framework of physics> David McAnally -------------- |
|
#3
| |||
| |||
| > Newton's Third Law is the statement that all forces can be paired in such If two equal and opposing forces occur simultaneously at the point of collision of two point particles, then those two particles are bound at the same point after the collision as the opposing forces cancel each other out. The result is two different point particles existing at the same point causing an infinity of further collisions. When did causality become a non-issue in the study of physical science? |
|
#4
| |||
| |||
| [Only registered users see links. ] (John Schoenfeld) writes: Rubbish. The forces do NOT act on the same particle. One of the forces affects the motion of one of the particles, and the other force affects the motion of the other particle. They do NOT affect the SAME particle, so your assessment above is complete garbage since it assumes something which is not true. Maybe it started for you when you started making assumptions which were not true, just like you did above. David McAnally -------------- |
|
#5
| |||
| |||
| [Only registered users see links. ] (John Schoenfeld) wrote in message news:<a98beaaa.0307031205.28a08ebe@posting.google. com>... Uh....the "forces" act on different bodies. If two bodies A and B interact then one force is the force that A exerts on B. The "equal and opposite" force is the force that B exerts on A. So the "equal and opposing forces act on completely different particles so the particles are not "bound" but accelerated in opposite directions. Unless they stick together due to some other forces etc. more to the point is WHY did causality become a non issue? The answer is that it became a non issue for no reason at all. Arf! Arfur. |
|
#6
| |||
| |||
| John Schoenfeld wrote: Dolt! The forces of Newton's third law are separate. Body A acts on body B and body B acts on body A with distinct forces, equal in magnitude and opposite direction. The 3-rd law is the conservation of classical momentum stated in other terms. It turns out the momentum must be defined in a relativistic manner for conservation to hold. As to the first and second law they are correct. One cannot distinguish between rest and uniform motion where there is no net force or acceleration. That is the whole point which Aristotle missed. He concluded that -any- motion requires a force. Not so. You are blovating. For low velocity motions Newton's laws are experimentally verified. Not in free space. The speed of light as measured by any known means is constant in free space when measure in inertial frames. Bob Kolker |
|
#7
| |||
| |||
| [Only registered users see links. ] (John Schoenfeld) writes: Wrong. The superposition principle states that the nett force on a body is equal to the superposition of the forces acting on the body, so that the time-derivative of the momentum of a body is the superposition of all the forces acting on the body. More generally, the nett force on a system of bodies is equal to the superposition of all the forces exerted on bodies internal to the system by bodies external to the system, so the time-derivative of the momentum of a system is equal to the superposition of all forces exerted on bodies internal to the system by bodies external to the system. The superposition principle tells us absolutely nothing about the internal dynamics of the bodies within a system. It only tells you about the time-derivative of the nett momentum of the system. Since a single body is a special case of a dynamical system, then I will give justification in the general case. First of all, Newton's Second Law of Motion tells us that the time-derivative of the momentum of a body is equal to the superposition of the forces acting on the body. Suppose a force F is exerted on a body A by a body B, and both bodies are internal to the system, then the partner of F in its pair is a force G, equal in magnitude and opposite in direction, which is exerted on the body B by the body A. It follows that the contribution to the time-derivative of the sum of the momenta of A and B from F and G is zero, as these forces cancel. So, upon defining the nett momentum of a system as the sum of the momenta of the individual component bodies, all forces exerted on bodies internal to the system by bodies internal to the system cancel in pairs. On the other hand, if a force F is exerted on a body A by a body C, and the body A is internal to the system and the body C is external to the system, then F contributes to the time-derivative of the sum of the momenta of the bodies in the system, and so to the time-derivative of the nett momentum of the system. On the other hand, the partner G of F in its pair is a force exerted on the body C by the body A, and so it is exerted on a body external to the system and does not contribute to the time-derivative of the sum of the momenta of the bodies of the system, and so it does not contribute to the time-derivative of the nett momentum of the system. In short, the time-derivative of the momentum of the system equals the sum of the time-derivatives of the momenta of the bodies which make up the system, which equals the superposition of the forces which are exerted on the bodies of the system. By Newton's Third Law of Motion, the forces between bodies internal to the system cancel each other in pairs. This leaves the forces exerted on bodies internal to the system by bodies external to the system, so that the time-derivative of the nett momentum of the system is equal to the superposition of the forces exerted on bodies internal to the system by bodies external to the system. The important point to note is that while the superposition determines the time-derivative of the nett momentum of the system, it has no bearing on the dynamics of the bodies within the system, since there is not enough information to determine the behaviour of the individual bodies. This means that because the forces cancel in a collision, then the momentum of the system of the two particles is conserved, but it gives you no additional information about the motion of the individual particles, so you can't make the assertion that you did. Physical theories are based on axioms and postulates. Newton built his Theory of Mechanics from certain axioms, which included his Three Laws of Motion. The Theory was then used to make certain predictions, and these predictions could be tested. Newtonian Mechanics is a consistent theory. On the other hand, you tried to add an assumption to the framework of the already established theory, and the assumption that you tried to add was inconsistent with that theory, and now you are attempting to condemn the theory as inconsistent merely because it happens to be inconsistent with your added assumption. Instead of condemning Newtonian Mechanics just because your own personal interpretation of the Laws is inconsistent, it would be better for you to take the trouble to learn the correct interpretation of the laws, and to understand, for example, that the superposition of forces exerted on internal bodies of a system by external bodies gives you no other information than the time-derivative of the total momentum of the system, and specifically, it gives you no additional information about the motion of the specific bodies in the system. David McAnally -------------- |
|
#8
| |||
| |||
| > >1. There exists two point masses moving towards each other. You still have it all wrong. POINT mass A has mass Ma. POINT mass B has mass Mb. At time t, a collision occurs at POINT p. So at time t we observe mass A and mass B existing simultaneously at point P. An equivalent observation would be that there exists a SINGLE POINT mass C with mass Ma+Mb existing at point P at time t. Also at time t, we have the paired force as predicted by Newtons 3rd law. Given that there is a single point mass at point p, then the superposition principle applies and the paired forces cancel each other out as predicted. Do you see the problem yet? Empirical evidence implies otherwise. Contact forces can never exist as they are always cancelled out at the point of contact. The problem with Newtons laws is that they do not define what a body is and isn't. Newtons laws do not prohibit the existence of point masses, and the above analysis I've showed clearly outlines a logical fallacy with these laws. |
|
#9
| |||
| |||
| [Only registered users see links. ] (John Schoenfeld) writes: No, I don't. I'm not the idiot who insists on misapplying Newtonian Mechanics. But not an indivisible point mass. That is an external assumption brought to us courtesy of the mind of Schoenfeld. Anything could happen. The masses could coalesce, as you suggest. Or they could bounce off each other elastically. Or they could explode into many different masses. By Newton's Laws, the ONLY thing that we know is that the nett momentum of the masses after the collision is equal to the nett momentum before. Only if we agree to the Schoenfeld-patented assumption that the mass at collsion is indivisible. Some others may think that the assumption is far too strong to make in the general case. Yes, it is perfectly clear to me. I see exactly where the problem is. The question is: Do YOU also see where the problem with yourself is yet? It is virtually impossible to observe the motion of an object on the Earth's surface in the absence of forces. As we are discussing Newtonian Mechanics, gravity is treated as a force, so there are no objects on the surface which are in the absence of forces. Empirical evidence tells us nothing about the validity of the First Law. This objection requires Schoenfeld's very own patent-pending assumption that upon collision, masses become one indivisible object, an assumption which is EXTERNAL to Newtonian Mechanics. Most people do not accept such an assumption, and so most people don't recognize the validity of your so-called objection. The fallecy that you showed required the ADDITIONAL assumption of Schoenfeld's very own assumption that point masses become one indivisible object upon collision. So the most that your fallacy shows is that your very own personal assumption is inconsistent with Newtonian Mechanics. It does not show an inconsistency within Newtonian Mechanics. David McAnally -------------- |
|
#10
| |||
| |||
| [Only registered users see links. ] (John Schoenfeld) wrote in message news:<a98beaaa.0307071740.395bc766@posting.google. com>... You're already wrong. Two bodies, even point masses, can NOT collide at a point P. Furthermore, the idea of point masses is wrong. Point masses don't exist, except as spread out over an area, corresponding to the Heisenburg Uncertainty Principles. Yes, I see the problem. But it isn't with Newton's Laws. As it turns out, bodies never actually collide. They simply exchange forces. One emits a carrier particle and the other absorbs it. Note that these are virtual particles, and in fact during the period of time between when the carrier particle is emitted by one particle and when it is absorbed by the other, threre IS a violation of Newton's Laws. So you are correct in a sense. However, macroscopically, the twin violations of Newton's Laws actually CANCEL eachother out. So you will never actually SEE a violation of Newton's Laws, even though for a short time, it does happen. However, the problem occurs when you try to apply your logic to normal, every day situations. And in THAT case it's wrong, because in all cases on the larger, more visible scale, the forces DO cancel eachother out. Well maybe there's something wrong with the concept of point masses. It would come as no surprise that your logic turns out to be correct, but that you are simply using false premises. Perhaps this explains why a point mass universe cannot actually exist. (...Starblade Riven Darksquall...) |
| Tags |
| wrong |
| Thread Tools | |
| Display Modes | |
|
|
| | ||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| Natural selection is proven wrong | gim | Biology Forum | 3 | 05-15-2009 07:43 PM |
| Can 250.000 people be ALL wrong? ................................. | philo | Physics Forum | 0 | 09-09-2008 05:17 AM |
| Can 250.000 people be ALL wrong? ................................. | Colin.D | Physics Forum | 0 | 09-08-2008 11:19 AM |
| Germinating Sassafras seeds - failure - what is wrong? | Harry Haller | Botany Forum | 4 | 10-25-2005 05:20 AM |
| Why Copenhagen Interpretation is Wrong | Consc | Physics Forum | 3 | 12-27-2004 09:38 PM |