The discussion revolves around the origins and implications of Newton's third law of motion, exploring how Newton may have predicted this law and its relationship to concepts like conservation of momentum. Participants engage in theoretical reasoning, observational insights, and the nature of postulates in physics.
Participants express various perspectives on the origins and implications of Newton's third law, with no clear consensus reached. Some agree on the importance of observational evidence, while others emphasize the role of postulates in physics.
The discussion includes references to historical context and the philosophical implications of postulates in physics, but lacks resolution on the specific insights Newton may have had regarding his third law.
By observation, like all physical laws, you can try out this expirement by yourself, try you push the wall, you'll notice that it's pushing you too. How do you jump ? You simply apply some force on the ground downward and it pushes you upward ! By repeating the same expirement, one can suggest that for any given force there is some reaction.amjad-sh said:How did Newton predict his third law? If we take the system as the whole universe Newton's third law leads that the net force of the system is zero.Did Newton have an insight about this?
amjad-sh said:How did Newton predict his third law?
DrStupid said:I think he started from conservation of momentum and the third law is a simple method to keep momentum constant. Of course the next question is: How did Newton predict conservation of momentum? Here I agree with Noctisdark that it results from experimental observations. As nobody ever observed that something changes its momentum without external interactions it is obvious to use this as an universal principle.
Although technically correct, there are infinite postulates possible from where to choose. Generally speaking, one postulate things after some observations and experiments.axmls said:Newton's third law is simply a postulate. It must simply be accepted, and then the conclusions drawn from it are put to the test. If the test confirms the postulate, then you've got a good postulate.