Is Newton's Third Law always true in every scenario?

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Discussion Overview

The discussion revolves around the validity of Newton's Third Law of Motion in various scenarios, particularly questioning whether forces are always exactly opposite and exploring exceptions or nuances in different contexts, such as curved spacetime or interactions involving magnetic forces. The scope includes theoretical considerations and conceptual clarifications.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether forces are always exactly opposite and seeks information on accelerating a mass upwards while eliminating or redirecting the recoil force.
  • Another participant suggests that in curved spacetime, the principle of "equal and opposite" forces may not hold, while asserting that it does in everyday Euclidean, inertial space.
  • A different participant argues that the essence of the third law relates to conservation of momentum, citing examples such as magnetic forces where forces are not equal and opposite, but momentum is conserved through other means.
  • One participant reflects on the interpretation of forces acting on different bodies, using the analogy of a horse pulling a cart to illustrate that forces may differ in such cases.
  • A participant reiterates the three laws of motion, prompting a question about their general correctness.
  • Another participant challenges the clarity of the original question regarding the general correctness of Newton's laws, suggesting it lacks specificity.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of Newton's Third Law, with some suggesting exceptions in specific contexts while others uphold its general validity. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the contexts in which Newton's laws apply, particularly concerning curved spacetime and the role of momentum in interactions involving magnetic forces.

treborly45
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Are the forces ALWAYS exactly opposite of each other?

Is there a way to accelerate a mass upwards, while having the "recoil" force travel on a horizontal plan or somehow completely eliminated?


Any and all information concerning this is much appreciated.

Rob
 
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Maybe events in curved spacetime would violate "equal and opposite." Otherwise, in our everyday Euclidean, inertial space, the law holds.
 
That's actually not quite true. The real content of the third law is the conservation of momentum; but, there are situations where the momentum of some third thing is relevant, without exactly being able to talk about a force.

The classic example of this is the magnetic force. If you consider two charged particles moving paths that intersect at a right angle, for example, you'll find that the magnetic forces on them are not equal and opposite. This seeming paradox is solved by the realization that electric and magnetic fields in combination can carry momentum. When one adds that momentum in, momentum is conserved without equal and opposite forces.
 
///Are the forces ALWAYS exactly opposite of each other?\\\

that's seems right if the forces was acts in diffrents bodies as if we have a horse hold a care ! so mybe the force acts on each body is diffrent ! isn't it :)
 
My question is this: are Newton's three laws of motion as general ideas about motion correct?

1. The first law is the principle of inertia. It states that an object in motion will conntinue to move unless acted on by an external force. And that an object at rest will remain at rest unless acted on by an external force.

2. The second law states that the change in momentum is proportional to the external force.

3. The third law is that for every action there is an equal and opposite reaction.
 
for which case u ask?

u ask as general if those r right or not? this is not a specified question ! sir ,
 

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