Dynamics Notes
Identifying Action and Reaction Forces

Forces are interactions between objects, like conversations are interactions between people. Newton's Third Law tells us that forces always arise in pairs, and two objects are always involved. The Newton's Third Law interaction is always of the form:


A pushes/pulls B.

B pushes/pulls A.

One of these forces is called the action force, and the other one is called the reaction force - it doesn't matter which is which. For example, if:

You push book. (Action force)

then Newton's Third Law says that:

Book pushes you. (Reaction force)

Identifying Reaction Forces Quiz

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last update January 1, 2009 by JL Stanbrough