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!
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.