How do action reaction force pairs arise?

  1. 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.

  2. jcsd
  3. rcgldr

    rcgldr 7,654
    Homework Helper

    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.
  4. 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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