How do action reaction force pairs arise?

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SUMMARY

Action-reaction force pairs arise as a fundamental principle of Newton's Third Law, which states that for every action, there is an equal and opposite reaction. This principle is not merely a consequence of electrostatic repulsion or energy conservation but is considered an axiom in classical mechanics. The discussion highlights that these force pairs can exist even without physical contact, such as in gravitational interactions between two bodies. Momentum conservation can also be used to derive these force pairs, but the concept of action and reaction is viewed as more foundational.

PREREQUISITES
  • Understanding of Newton's Third Law of Motion
  • Basic knowledge of classical mechanics
  • Familiarity with concepts of force and interaction
  • Awareness of momentum conservation principles
NEXT STEPS
  • Study the implications of Newton's Third Law in various physical systems
  • Explore gravitational interactions and their force pairs
  • Learn about momentum conservation in collision scenarios
  • Investigate the role of action-reaction pairs in non-contact forces
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Students of physics, educators teaching classical mechanics, and anyone interested in understanding the foundational principles of force interactions in physical systems.

echolett
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Hi guys,

What is the reason for action-reaction force pairs to arise?
Is it a consequence of electrostatic repulsion due to interaction of the 2 bodies, or can it be explained using energy conservation or momentum conservation.

Thanks!
 
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echolett said:
What is the reason for action-reaction force pairs to arise?
It's an axiom or postulate that is just assumed to be self-evident and true. I'm not sure there's a way to prove it. Almost all forces invoved some type of reaction if you look at a situation from a large enough scale, and consider things like how much the Earth is affected by a car acclerating on it's surface.

In some cases, a Newton 3rd law pair doesn't require physical contact, such as gravity, where the third law pair is the equal and opposing attractive force on each body in a two body system.
 
You could derive force pairs from momentum conservation of arbitrary pairs of objects, but we tend to think of actio = reactio as being more fundamental.
 

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