D H Posted January 14, 2009 Posted January 14, 2009 can you give me some equation that illustrates 3rd law? Sure. Given a system of N particles, the force [math]{\boldsymbol F}_{a,b}[/math] exerted by particle a on particle b and the force [math]{\boldsymbol F}_{b,a}[/math] exerted by particle b on particle a are related by [math]{\boldsymbol F}_{b,a} = -\,{\boldsymbol F}_{a,b}[/math] force ALWAYS comes in pairs?what in the world? can you document that statement? I just did (see the above equation). Forces that obey Newton's third law (e.g. most classical forces) always come in pairs. One way to look at Newton's third law is that forces represent interactions between pairs of objects that conserve momentum. Interactions between objects and the conservation laws are more fundamental (and more universal) than Newton's laws of motion.
PlayStationX Posted January 14, 2009 Posted January 14, 2009 (edited) --- Newton's laws of motion ---- Sure. Given a system of N particles, the force... F(b,a) = -F(a,b) uh, huh... i see collision, but how well it describes motion? Forces that obey Newton's third law (e.g. most classical forces) always come in pairs. One way to look at Newton's third law is that forces represent interactions between pairs of objects that conserve momentum. ok, ill explain everything now... Q1: what are we talking about? A1: forces and motion Q2: what forces? A2: field forces, like gravity and magneto-electric fields Q3: do we have any equations of motion for them? A3: yes. say, force between two charges: F= m*a = k*Q1*Q2/r^2 Q4: holy smoke! that's Newton's 3rd law!? A4: yes, force is equal and opposite Q5: ...and what about magnetic force? A5: @$#%... shut up! Q6: hey, don't yell at me, i thought we are the same person?! forces do not come in pairs, number TWO is simply because we are dealing with two objects and each of these objects has its own magneto-electric field forces, hence they come in pair just because that's how situation is initialized. force pairs are not a fact of "natural occurrence", but the consequence of that Newton is talking about TWO objects. with all that said, let me now say that some forces DO COME in PAIRS... magneto-electric, and Yin-Yang. to summarize: - this is what 3rd law is all about: F= m*a = G*m1*m2/r^2 "To every action there is an equal and opposite reaction.", is misleading interpretation of that equation. it should not be stated as law, since it is only a consequence of 'real' law of interaction - 'inverse square law of attraction/repulsion'. Edited January 14, 2009 by PlayStationX
Baby Astronaut Posted January 14, 2009 Posted January 14, 2009 PlayStationX, they are not wrong. If anything, you're probably better off claiming the notion of "a pair" is limited rather than wrong, since obviously its math has been proven to support it millions of times with endless calculations by thousands of people. From what I can understand, what you're saying is that back in the day, someone had began making these calculations using only two equal and opposite variables, when in fact they could have used any number of equal and opposite variables, not just two. Correct? I'm not fluent in math, so can't test your equations. But I'm curious what the "r" signifies in F= m*a = G*m1*m2/r^2.
PlayStationX Posted January 14, 2009 Posted January 14, 2009 (edited) "Yes, the rock pushes back on you with as much force as you push on it. ", - only if you are talking about some other rock that does not move when you push it. if it moves, then you obviously pushed it stronger: F(you)=m*a - F(stone)=m*a; if there was any movement, you can see from the formula that resisting force had to be less than applied force for it to happen. this is all wrong, i tried to contra-argue in the way NASA explains 3rd law, but i failed. NASA's explanation doesn't seem right either, they never mention EQUALITY of the forces, rather opposite... Explanation of Newton's third law by NASA employee: -"...if thrust is greater than the drag, plane will accelerate." Merged post follows: Consecutive posts merged But I'm curious what the "r" signifies in F= m*a = G*m1*m2/r^2. ay caramba! r, is the distance between two objects (masses), in that case. if you work with charges like protons and electrons, then it is a distance between charges. Newton's law of universal gravitation http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation Coulomb's law http://en.wikipedia.org/wiki/Coloumb_law from this we can take a note of similarity of macrocosmos with microcosmos and that charge and mass are two fundamental concepts of what we call material world. From what I can understand, what you're saying is that back in the day, someone had began making these calculations using only two equal and opposite variables, when in fact they could have used any number of equal and opposite variables, not just two. Correct? no, i think Newton was actually working on formulas to describe planetary motion when he came up with his 3 laws of motion. i did not say any of the formulas are wrong, just that interpretation is confusing and that all three laws actually talk about one and the same thing, so they could be much better formulated. for example, once you state 2nd law: F= m*a, the 1st law comes out as a consequence of it: no force -> no acceleration -> no change in velocity/direction. 3rd law, as i said, is not a good law, because it is only a consequence of "inverse square law". Edited January 14, 2009 by PlayStationX Consecutive post/s merged.
swansont Posted January 14, 2009 Posted January 14, 2009 are you saying you disagree with it? If it's a statement about the 3rd law, yes. Sisyphus has already explained why it is wrong. The statement itself is true, but the quote didn't say it was explaining the third law. You did. I'd like to confirm who is misinterpreting the third law. of course there is such thing as "resisting force". -"Inertia is the resistance of an object to a change in its state of motion." http://en.wikipedia.org/wiki/Inertia Inertia is not a force. If I exert a net force on an object it will accelerate. If the object has a large mass, the acceleration will be small. Merged post follows: Consecutive posts mergedI'm not fluent in math, so can't test your equations. But I'm curious what the "r" signifies in F= m*a = G*m1*m2/r^2. r is the separation distance between the two masses
PlayStationX Posted January 14, 2009 Posted January 14, 2009 (edited) Inertia is not a force. If I exert a net force on an object it will accelerate. If the object has a large mass, the acceleration will be small. by saying that, do you think you've explained the reason why you refuse to call it a force? where is that "equal and opposing" force in your example? inertia? - "The vis insita, or innate force of matter is a power of resisting, by which every body, as much as in it lies, endeavors to preserve in its present state, whether it be of rest, or of moving uniformly forward in a straight line." Newton 1st law is all about inertia, that's how its called - "law of inertia" - "..favor the mathematically useful definition of inertia as the measure of a body's resistance to changes in momentum or simply a body's inertial mass. Mass, m, denoted something like amount of substance or quantity of matter. And at the same time mass was the quantitative measure of inertia of a body. But mass as related to 'inertia' of a body can be defined also by the formula: F = m*a " where 'F' stand for FORCE http://en.wikipedia.org/wiki/Inertia If it's a statement about the 3rd law, yes. Sisyphus has already explained why it is wrong. The statement itself is true, but the quote didn't say it was explaining the third law. You did. I'd like to confirm who is misinterpreting the third law. are you having me on? i gave you link then, here is again: http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion scroll down to the part about 3rd law and you will see a video there: "Explanation of Newton's third law by NASA employee.", quote is right there on the screenshot. i dont mean to argue NASA's point, i have my beautiful points: A.) this is where "equal and opposite force" came from and what 3rd law is all about: F= G*m1*m2/r^2 B.) once you state 2nd law: F= m*a, the 1st law comes out as a consequence of it: no force -> no acceleration -> no change in velocity/direction. 3rd law, as i said, is not a good law, because it is only a consequence of "inverse square law" (point A). C.) 1st, 2nd & 3rd law combined: only force accelerates and unless opposed by an equal force, it always does so. F= m*a so, if i'm confused, if i'm the one who did not understand the laws of motion and if i am the one who is misinterpreting, then please.... show me! Edited January 14, 2009 by PlayStationX
Sisyphus Posted January 14, 2009 Posted January 14, 2009 so, if i'm confused, if i'm the one who did not understand the laws of motion and if i am the one who is misinterpreting, then please.... show me! Several people already have, including a couple of real live physicists. But again: forces act in equal and opposite pairs. Each force in this pair can be acting on a different body, which is how things move. If you push on a rock, there are two equal and opposite forces: the force acting on the rock in the direction you push it, and the force acting on you in the opposite direction. Once again, your misunderstanding is in assuming the opposite forces have to be acting on the same object, as if they were thrust and drag.* You push on the rock, and the rock pushes on you. The rock is not pushing itself in the opposite direction. You are each being pushed apart with the same force. *And once again, thrust and drag are not an example of a force pair. I'll repeat myself: The thrust pushes the air backwards with a certain amount of force, thereby pushing the plane forwards with an equal force. That is thrust. As the plane moves through the air, it has to push the air in front of it out of the way. The air then pushes back on it with an equal force. That is drag. There are four forces in total, in two opposite and equal pairs[/b']. One force from each pair is acting on the plane itself. I don't know what else I can say. Except, I guess, that if you're deliberately wasting our time, then a hex on you and your loved ones.
PlayStationX Posted January 14, 2009 Posted January 14, 2009 (edited) Several people already have, including a couple of real live physicists. But again: forces act in equal and opposite pairs. what are you doing? i already responded to all you have said, you keep repeating your confusion as if you did not even read what was said. it is insulting to make people repeat themselves. *And once again, thrust and drag are not an example of a force pair. I'll repeat myself: are you talking to me? sorry, i do not know what to tell you, i never said anything like that. please quote what are you referring to. Originally Posted by me, yesterday, in case you missed it The thrust pushes the air backwards with a certain amount of force, thereby pushing the plane forwards with an equal force. That is thrust. As the plane moves through the air, it has to push the air in front of it out of the way. The air then pushes back on it with an equal force. That is drag. There are four forces in total, in two opposite and equal pairs. One force from each pair is acting on the plane itself. sheesh, i see now... you are arguing with NASA? cant help you there, but i agree with you, they seem confused about it as well. no one even responded to any of these, even less proved it wrong: A.) this is where "equal and opposite force" came from and what 3rd law is all about: F= G*m1*m2/r^2 B.) once you state 2nd law: F= m*a, the 1st law comes out as a consequence of it: no force -> no acceleration -> no change in velocity/direction. 3rd law, as i said, is not a good law, because it is only a consequence of "inverse square law" (point A). C.) 1st, 2nd & 3rd law combined: only force accelerates and unless opposed by an equal force, it always does so. F= m*a now, please be specific and argument your insults, what do you say is wrong? Edited January 14, 2009 by PlayStationX
iNow Posted January 14, 2009 Posted January 14, 2009 Having just read through this and other threads, PlaystationX is clearly trolling. [/2¢]
D H Posted January 14, 2009 Posted January 14, 2009 [math]{\boldsymbol F}_{b,a} = -\,{\boldsymbol F}_{a,b}[/math][/quote']uh, huh... i see collision, but how well it describes motion? The above equation is very generic. It pertains, for example, to gravitation and the electrostatic force. Collisions are simply a manifestation of the electrostatic force. ok, ill explain everything now... Q1: what are we talking about? A1: forces and motion Q2: what forces? A2: field forces, like gravity and magneto-electric fields Q3: do we have any equations of motion for them? A3: yes. say, force between two charges: F= m*a = k*Q1*Q2/r^2 Q4: holy smoke! that's Newton's 3rd law!? A4: yes, force is equal and opposite F=m*a is Newton's second law, not Newton's third law. One way of thinking about "F=m*a" is that it defines force (net force, actually) in terms of acceleration. The Coulomb force, F=ke*Q1*Q2/r2 is a good example of Newton's third law. That expression is the magnitude of the Coulomb force of charge 1 on charge 2 and the Coulomb force of charge 2 on charge 1. To get to Newton's third law, you have to go to the full vector form of the Coulomb force: [math]{\boldsymbol F}_1 = k_e\,\frac{Q_1Q_2}{r^2}{\hat{\boldsymbol r}}_{2\to 1}[/math] [math]{\boldsymbol F}_2 = k_e\,\frac{Q_1Q_2}{r^2}{\hat{\boldsymbol r}}_{1\to 2} = -{\boldsymbol F}_1[/math] forces do not come in pairs, number TWO is simply because we are dealing with two objects and each of these objects has its own magneto-electric field forces, hence they come in pair just because that's how situation is initialized. force pairs are not a fact of "natural occurrence", but the consequence of that Newton is talking about TWO objects. Forces do come in pairs. Moreover, they come in equal-but-opposite pairs. Understand this and you will understand Newton's third law. Explanation of Newton's third law by NASA employee:-"...if thrust is greater than the drag, plane will accelerate." When I get back to work tomorrow at NASA (I'm on vacation now) I will try to chase down this example. It is a terrible example of Newton's third law. The third law reaction to thrust is the rearward acceleration of the air flow by the plane's engines or propellers. The third law reaction to drag is the forward acceleration of the airflow by the plane's passive surfaces. Third law forces always act on different objects. no, i think Newton was actually working on formulas to describe planetary motion when he came up with his 3 laws of motion. i did not say any of the formulas are wrong, just that interpretation is confusing and that all three laws actually talk about one and the same thing, so they could be much better formulated. for example, once you state 2nd law: F= m*a, the 1st law comes out as a consequence of it: no force -> no acceleration -> no change in velocity/direction. 3rd law, as i said, is not a good law, because it is only a consequence of "inverse square law". Newton's first law defines the concepts of momentum and inertial reference frames. Newton's second law defines force in terms of behavior. Newton's third law says forces, whatever they are, come in equal but opposite pairs. There is no mention of inverse square laws. Good thing, that: You're wrong. Hooke's law is not an inverse square law and it too obeys Newton's third law. anyway, -"To every action there is always opposed an equal reaction.", is false. You would better serve yourself if you drop the attitude. It is impeding your ability to learn. The forces you encounter in the everyday world do come in equal but opposite pairs. 1
Sayonara Posted January 14, 2009 Posted January 14, 2009 it is insulting to make people repeat themselves. It certainly is, and yet you keep asking for examples to demonstrate things which have already been demonstrated by example. Your MO is hardly subtle, is it? sheesh, i see now... you are arguing with NASA? This is a science forum. There is nothing preventing anyone from 'arguing' with NASA. Whether or not they make a compelling case for their disagreement is up to them. Read what people are telling you. If you don't think it addresses your points, then explain why instead of ignoring them and just repeating the same query. Otherwise this could go on forever while people blindly try to edge closer to understanding what you are going on about.
swansont Posted January 14, 2009 Posted January 14, 2009 by saying that, do you think you've explained the reason why you refuse to call it a force? where is that "equal and opposing" force in your example? inertia? - "The vis insita, or innate force of matter is a power of resisting, by which every body, as much as in it lies, endeavors to preserve in its present state, whether it be of rest, or of moving uniformly forward in a straight line." Newton 1st law is all about inertia, that's how its called - "law of inertia" - "..favor the mathematically useful definition of inertia as the measure of a body's resistance to changes in momentum or simply a body's inertial mass. Mass, m, denoted something like amount of substance or quantity of matter. And at the same time mass was the quantitative measure of inertia of a body. But mass as related to 'inertia' of a body can be defined also by the formula: F = m*a " where 'F' stand for FORCE http://en.wikipedia.org/wiki/Inertia emphasis added — I've highlighted the relevant part of the quote. Inertia can be equated to the body's inertial mass. It's not a force. It's the mass. are you having me on? i gave you link then, here is again: http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion scroll down to the part about 3rd law and you will see a video there: "Explanation of Newton's third law by NASA employee.", quote is right there on the screenshot. The employee could have said that there are 1000 grams in a kilogram as part of that video. It would be true, and yet not be an explanation of the 3rd law. i dont mean to argue NASA's point, i have my beautiful points: A.) this is where "equal and opposite force" came from and what 3rd law is all about: F= G*m1*m2/r^2 B.) once you state 2nd law: F= m*a, the 1st law comes out as a consequence of it: no force -> no acceleration -> no change in velocity/direction. 3rd law, as i said, is not a good law, because it is only a consequence of "inverse square law" (point A). C.) 1st, 2nd & 3rd law combined: only force accelerates and unless opposed by an equal force, it always does so. F= m*a so, if i'm confused, if i'm the one who did not understand the laws of motion and if i am the one who is misinterpreting, then please.... show me! The third law is decidedly NOT only a consequence of the inverse-square law. You can observe it in e.g. a spring between two masses that are held together and then released (a simple explosion). That force is linear in x. (Edit: I see D H mentions the example of Hooke's law as well)
PlayStationX Posted January 14, 2009 Posted January 14, 2009 Having just read through this and other threads, PlaystationX is clearly trolling. i like your arguments and inability to understand. try to define word "troll", and you may notice that it is not me, but the face you see in a mirror.
insane_alien Posted January 14, 2009 Posted January 14, 2009 lol inow a troll? that is indeed a funny proposition. iNow actually contributes a lot to this forum, he also engages in proper discussion and has accepted defeat a few times. not the mark of a troll, you on the other hand...
PlayStationX Posted January 14, 2009 Posted January 14, 2009 (edited) F=m*a is Newton's second law, not Newton's third law... The Coulomb force, F=ke*Q1*Q2/r2 is a good example of Newton's third law. i do not see a need for your comment, but im glad we agree. Forces do come in pairs. Moreover, they come in equal-but-opposite pairs. Understand this and you will understand Newton's third law. oh mercy! i can not understand it if you can not explain it. i've given you my explanation, why you are wrong, but instead to comment on that you keep repeating your false logic. what is the point of saying anything without providing reason and arguments for it? 1.) show my logic is false 2.) show your logic is true forces do not "come" in pairs, that means nothing. i thought you understood this from above equation. do you not see that only two forces in that equation have to do with two charges? take one charge, then you will notice forces do not come in pairs, but they come with a number of objects in your equation, in this case two. is there any other force there? When I get back to work tomorrow at NASA.. i wish you were joking. btw, i know of some bugs NASA, and the rest of the world, have in simulation software. There is no mention of inverse square laws. Good thing, that: You're wrong. Hooke's law is not an inverse square law and it too obeys Newton's third law. Hooke's law.. uh, huh. interaction within it is still the same interaction between charged particles, but i thought you agreed on inverse square law? did you not say this: -"The Coulomb force, F=ke*Q1*Q2/r2 is a good example of Newton's third law" anyway, what statement of mine do you say is wrong? i find it funny everyone is telling me "wrong", but no one cares to actually QUOTE what are they referring to. please quote, it will avoid misinterpretation. You would better serve yourself if you drop the attitude. It is impeding your ability to learn. The forces you encounter in the everyday world do come in equal but opposite pairs. nonsense. matter interact via electromagnetic fields, so there is no other forces you could possibly be talking about here. explain, how does electromagnetic force "COME" in pair? of course, you will fail to explain this, since it is high-school knowledge that electromagnetic field is a property of every single charged particle. forces we are talking about do not "come" by themselves, even less in pairs - they come with charged particles. every charge has it own SINGLE electric and magnetic force. forces DO NOT come in pairs. force pairs are consequence of two objects interacting - take one charge out of Coulomb equation and tell me where is you force pair then? Merged post follows: Consecutive posts mergedSayonara³, It certainly is, and yet you keep asking for examples to demonstrate things which have already been demonstrated by example. Your MO is hardly subtle, is it? that is not true, please quote it. Read what people are telling you. If you don't think it addresses your points, then explain why.. sure, to address something you need to quote it, then provide arguments for the opinion. Merged post follows: Consecutive posts merged Inertia can be equated to the body's inertial mass. It's not a force. It's the mass. wake up, do you not see a word "force" i that definition? LOOK -----> F(inertia)= m*a F= force m= mass no further comment on this, you can call it whatever you like The employee could have said that there are 1000 grams in a kilogram as part of that video. It would be true, and yet not be an explanation of the 3rd law. sure, the true explanation is the one i provided. The third law is decidedly NOT only a consequence of the inverse-square law. You can observe it in e.g. a spring between two masses that are held together and then released (a simple explosion). That force is linear in x. (Edit: I see D H mentions the example of Hooke's law as well) finally we have normal conversation again, with quotes and arguments. the third law *IS* a consequence of the "inverse-square law". (referring to Coulomb's law and law of gravity) it simply can not be anyhow else, because the only way material world interacts is fundamentally a result of interaction between these force fields. all the equations for such interaction follow the law of INVERSE SQUARE. im talking about fundamentals, free your mind and look at the full picture. Edited January 14, 2009 by PlayStationX Consecutive post/s merged.
Sisyphus Posted January 14, 2009 Posted January 14, 2009 By "come in pairs," all that is meant is that no force can be exerted on anything without an equal and opposite force exerted on something else, i.e. what everybody (including Isaac Newton) has been saying. This is a fact. Outright denial of this fact is not faulty logic, per se, it's just a false statement. That's why it's difficult to argue with you.
swansont Posted January 14, 2009 Posted January 14, 2009 forces do not "come" in pairs, that means nothing. i thought you understood this from above equation. do you not see that only two forces in that equation have to do with two charges? take one charge, then you will notice forces do not come in pairs, but they come with a number of objects in your equation, in this case two. is there any other force there? Is it possible for you to exert a force on an object without it exerting a force on you? If yes, give an example. If no, then you must at least provisionally agree that forces come in pairs. i wish you were joking. btw, i know of some bugs NASA, and the rest of the world, have in simulation software. Hooke's law.. uh, huh. interaction within it is still the same interaction between charged particles, but i thought you agreed on inverse square law? did you not say this: -"The Coulomb force, F=ke*Q1*Q2/r2 is a good example of Newton's third law" An example of the law, not the law itself. anyway, what statement of mine do you say is wrong? i find it funny everyone is telling me "wrong", but no one cares to actually QUOTE what are they referring to. please quote, it will avoid misinterpretation. nonsense. matter interact via electromagnetic fields, so there is no other forces you could possibly be talking about here. explain, how does electromagnetic force "COME" in pair? of course, you will fail to explain this, since it is high-school knowledge that electromagnetic field is a property of every single charged particle. forces we are talking about do not "come" by themselves, even less in pairs - they come with charged particles. every charge has it own SINGLE electric and magnetic force. forces DO NOT come in pairs. F=ke*Q1*Q2/r^2 describes the force on Q1 and Q2. You cannot have a force on Q1 without having the force on Q2. force pairs are consequence of two objects interacting - take one charge out of Coulomb equation and tell me where is you force pair then? One charge does not exert or feel a force of there are no other charges around.
PlayStationX Posted January 14, 2009 Posted January 14, 2009 (edited) By "come in pairs," all that is meant is that no force can be exerted on anything without an equal and opposite force exerted on something else, i.e. what everybody (including Isaac Newton) has been saying. i understand what is "meant" by it, but i hope that you too can understand what it actually means and what is the real cause of it. This is a fact. Outright denial of this fact is not faulty logic, per se, it's just a false statement. That's why it's difficult to argue with you. it is not a fact, it is very bad wording and vague phrase. chickens COME out of an egg, forces DO NOT come out of anywhere. they are SINGLE property of every single charged particle - therefore, force "COME" in singles as a single property of every single charge. it is funny that you want to accept such a fundamental statement about electromagnetic fields based on some half-baked, quasi law from 1687. if you really want to know how forces "COME TO BE", then better try some theory that actually deals with these forces. please understand, Newtons laws are redundant. you can sum it all up with this: F = m*a = k* Q1*Q2/r^2 that is mathematical truth that describes all three laws... try it, try to ask any question three laws are supposed to answer and i will too answer that by only using above formula. do you accept the challenge? Merged post follows: Consecutive posts merged Is it possible for you to exert a force on an object without it exerting a force on you? If yes, give an example. If no, then you must at least provisionally agree that forces come in pairs. yes, i think so - magnetic fields do not seem to bow to 3rd law. im not saying the law is wrong, per se - im saying that by explaining it like that people will never realize what is the real CAUSE for it and WHY is it so. i agree with your first sentence, it is a statement of causality, nothing wrong with it. however, to say "force *COME* in pairs" is a statement about the origin of the electromagnetic and gravity fields. it is so very much unnecessary statement in some law of motion from 1687. F=ke*Q1*Q2/r^2 describes the force on Q1 and Q2. You cannot have a force on Q1 without having the force on Q2. "force on"? im not talking about force on or under, force is within and around Q1, with or without Q2. the correct statement is: - "forces came in pairs when two object interact", which sounds ridiculous because it uncovers banality of the statement. you could also say: - "forces come in triplets when three objects collide" you could also say: - "forces come in n-lets when n objects collide" you can not say: -"forces come in pairs", because it is not true for every case, but only the case when two objects interact, and even there we can have linear and angular momentum. i feel silly now explaining this again, is it not everything obvious from here: F = m*a = k* Q1*Q2/r^2 ?? One charge does not exert or feel a force of there are no other charges around. you speak now about EXERTING force, but before you said "forces COME in pairs", and my argument is about that. it does not "feel" a force but it nevertheless posses its own force. the force for that particular charge DID NOT COME in PAIR, did it? forces DO NOT COME in PAIRS, they do not even interact in pairs(only), they interact in whatever given number is there. Edited January 14, 2009 by PlayStationX Consecutive post/s merged.
Sisyphus Posted January 15, 2009 Posted January 15, 2009 they are SINGLE property of every single charged particle - therefore, force "COME" in singles as a single property of every single charge. No, the charge is the property, not the force. Force, by definition, is something exerted on something else, hence forces only occur between charged particles. Any amount of force can be exerted on these, or none, but if there is, then there has to be an equal and opposite force exerted on something else. you could also say: - "forces come in triplets when three objects collide"you could also say: - "forces come in n-lets when n objects collide" No, you could not. With three bodies there are six forces (assuming they're all interacting with one another). Each body exerts an equal and opposite force on each other body, resulting in this case in three force pairs. With four bodies there would be 12, with five there would be 20, etc. it does not "feel" a force but it nevertheless posses its own force. No, it does not. It possesses a charge. It seems that the main issue (currently) is one of defintions, specifically that you're using the term "force" incorrectly?
Sione Posted January 16, 2009 Posted January 16, 2009 (edited) Interesting. One of the confusing factors in this discussion is that "force" can be noun as well as verb, say something that exist vs. something that happens (exerting force = forcing). No, it does not. It possesses a charge. It seems that the main issue (currently) is one of defintions, specifically that you're using the term "force" incorrectly? PSX talks about noun, about something that exists, while Sisyphus talks about verb and other than that there is no much _real disagreement. The essence of the problem is that we can not measure field forces directly as a single property. We can't really confirm it exists until something happens. This is in agreement with "force come in pairs", but it doesn't mean the ability to exert the force was not there before. Wikipedia says: "The fact that the electromagnetic field can possess momentum and energy makes it very real... For example, the gravitational field is a vector field because every point needs a vector to represent the magnitude and direction of the force." The issue is indeed the one of definitions, thought I think that is exactly what PSX tried to illustrate and I agree Newton's laws are badly defined as well as that 1st law is superfluous given the 2nd law. No, the charge is the property, not the force. Force, by definition, is something exerted on something else, hence forces only occur between charged particles. Wikipedia says: "In physics, a force is that which can cause an object with mass to accelerate."; In that respect force is a property of charge or mass as an ability to perform interaction rather than consequence of interaction. Interaction itself could not have happened if that ability was not there before and the only question is how to call that ability. PSX calls it "force", while Sisyphus would probably call it "energy" or "potential energy"? Wikipedia says: "Instead of a force, often the mathematically related concept of a potential energy field can be used for convenience." Edited January 16, 2009 by Sione
petebro Posted January 19, 2009 Posted January 19, 2009 Motion without insulting peoples intelligence is brought about simply by a energy force ,Brownian motion may be a more comprehensive study of the science moreover the means of achieving motion perpetual motion is a subject i find interesting because it demonstrates that every action has an equal and opposite reaction obviously we look at expending energy while cycling and create motion if we then look at the wheel of the bike we have opposite forces within the circle within motion our planet for example may appear to have forces moving in one direction yet the is momentum in the opposite direction use the equator as our division and look at two forces working in opposite directions, do you agree? the tractor beam of light is adding to the planets momentum and general relativity explains more fully the interaction of moving body,s .and the attraction due to a electromagnetic force, its interesting because science is like meccano it is joined together . And the joy is we can take it peacemeal , energy quanta , photon discharges we can end up or begin from big bang , chow .
Sione Posted January 20, 2009 Posted January 20, 2009 the tractor beam of light is adding to the planets momentum... I like the sound of that. All motion is achieved via COLLISION. Without collision everything will move with constant velocity, which is what 1st Newton law says. It is important to understand that every single particle is in CONSTANT COLLISION with any other particle in the universe. This is simply because electromagnetic and gravity fields extend to infinity and therefore every single particle influences, exerts the force or in other words "collides" with every other particle all the time. When this collision is unbalanced, i.e. more force comes from one side, then object accelerates.
swansont Posted January 21, 2009 Posted January 21, 2009 I like the sound of that. All motion is achieved via COLLISION. Without collision everything will move with constant velocity, which is what 1st Newton law says. It is important to understand that every single particle is in CONSTANT COLLISION with any other particle in the universe. This is simply because electromagnetic and gravity fields extend to infinity and therefore every single particle influences, exerts the force or in other words "collides" with every other particle all the time. When this collision is unbalanced, i.e. more force comes from one side, then object accelerates. The collision is never "unbalanced" in terms of force or momentum. What is the collision that accelerates a charge in an electric or magnetic field? Remember, we're discussing classical physics here.
Sione Posted January 23, 2009 Posted January 23, 2009 (edited) The collision is never "unbalanced" in terms of force or momentum. I think you are referring to 'conservation' of momentum, I was talking about balanced/unbalanced forces and referring to what OP said about what Newton said: newton's 1st law states that acceleration can only be acheived if an external UNBALANCED force acts upon an object What is your understanding of Newton's first law? "A body continues to maintain its state of rest or of uniform motion unless acted upon by an external unbalanced force." What is the collision that accelerates a charge in an electric or magnetic field? Remember' date=' we're discussing classical physics here.[/quote'] "Collision" is not common term for electromagnetic interaction. However, if you let me define "constant collision", then its meaning can be derived from the existing definition: col⋅li⋅sion –noun 3. Physics, the meeting of particles or of bodies in which each exerts a force upon the other, causing the exchange of energy or momentum. in⋅ter⋅ac⋅tion –noun 1. reciprocal action, effect, or influence. 2. Physics, any of four fundamental ways in which elementary particles and bodies can influence each other, classified as strong, weak, electromagnetic, and gravitational. collision = interaction no interaction = no collision Basically, we can say two particles collide when they "interact" with each other, where 'interact' means - "change velocity, direction or spin". If, for example, gravity field goes to infinity, then we can say it "interacts" with any other particle, no matter how far away and no matter how small that "influence" might be, it is still not zero and, in a way, they are "colliding". Their 'mass bodies' are not in contact, but their 'field forces' are colliding/interacting nevertheless. Edited January 23, 2009 by Sione
Sayonara Posted January 23, 2009 Posted January 23, 2009 Although those definitions state "physics" at the start of them, you need to be very careful about using dictionary definitions for technical scientific discussions. Especially in physics, where terms are defined and used very precisely.
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