Action and Reaction     Newton's third law of motion states that every action has an equal and opposite reaction. This means that forces always act in pairs. First an action occurs, such as two skateboarders pushing together. Then a reaction occurs that is equal in strength to the action but in the opposite direction. In the case of the skateboarders, they move apart, and the distance they move depends on how hard they first pushed together.     You might think that actions and reactions would cancel each other out like balanced forces do. Balanced forces, which are also equal and... Show more

Action and Reaction    
Newton's third law of motion states that every action has an equal and opposite reaction. This means that forces always act in pairs.

First an action occurs, such as two skateboarders pushing together. Then a reaction occurs that is equal in strength to the action but in the opposite direction. In the case of the skateboarders, they move apart, and the distance they move depends on how hard they first pushed together.    
You might think that actions and reactions would cancel each other out like balanced forces do. Balanced forces, which are also equal and opposite, cancel out because they act on the same object. Action and reaction forces, in contrast, act on different objects, so they don't cancel out. In fact, they often result in motion.    

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