# Two objects exert forces on each other, will the reactions affect them?

Two objects go in against each other, and then they collide, will object 1, exerting force 1, necessarily get on it a reaction equal in magnitude and opposite in direction?

EDIT:- In my book it only says "for every action there is always opposed an equal reaction". But after reading on Newton's third law on Wikipedia, I read this "The action and the reaction are simultaneous"; it's not an intuitive statement (it sounds more like an object gets a reaction after an action), but anyway that solves my problem. If you care to explain how the two forces are always simultaneous please do.

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It sounds like you may have been confused because intuitively, you would think a reaction occurs after the action, in response to it. As you've found, that is not what Newton's third law is saying. The reaction force is not a response to the action. For this reason, some people don't like the statement "For every action, there is an equal and opposite reaction."

A better statement of Newton's third law is to say that forces always occur in pairs. It is impossible for object A to exert a force on object B without object B also exerting a force on object A. The two forces are simultaneous, of equal magnitude, and in opposite directions.

Mathematically, this is stated as

$$\mathbf{F}_{AB} = -\mathbf{F}_{BA}$$

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In Newtonian mechanics, yes. This is Newton's third law, as Chris Gerig pointed out in the comments.

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