Newton's Third Law of Motion
When one object exerts a force on another object, the second object instantaneously
exerts a force back on the first. These two forces are always equal in magnitude
but opposite in direction. These forces act on different objects and never on the
same object.
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Equal & Opposite
Action and reaction forces are always equal in magnitude but opposite in direction.
If you push with 10 N, you get pushed back with 10 N.
💥
Different Objects
Action and reaction forces always act on different objects. They never cancel out
because they don't act on the same body.
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Simultaneous
Action and reaction occur simultaneously. There's no time delay - the moment
you push, you get pushed back instantly.
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Different Accelerations
Equal forces can produce different accelerations if masses are different.
F = ma, so smaller mass means larger acceleration.
🎯 Common Action-Reaction Pairs
Walking: Foot pushes road backward
⇄
Road pushes foot forward
Gun: Gun pushes bullet forward
⇄
Bullet pushes gun backward (recoil)
Jumping: Sailor pushes boat backward
⇄
Boat pushes sailor forward
Collision: Player A pushes Player B
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Player B pushes Player A equally