Newton's Third Law

on . Posted in Classical Mechanics

Newtons third lawNewton's third law of motion, also known as the law of actions and reaction, states that for every action, there is an equal and opposite reaction. It means that whenever one object exerts a force on a second object, the second object exerts an equal and opposite force back on the first object.  In simpler terms, if object A applies a force on object B, then object B simultaneously applies an equal and opposite force on object A.  These two forces always occur as a pair, acting on two different objects.

For example, consider a person pushing a heavy box.  According to Newton's third law, as the person pushes the box forward with a certain force, the box exerts an equal and opposite force backward on the person.  These two forces are known as an action reaction pair.  It is important to note that the action and reaction forces act on different objects and are equal in magnitude but opposite in direction.  The forces do not cancel each other out because they act on different objects.  They are simply two parts of the same interaction.

Newton's third law of motion applies to all interactions in the universe.  It is the underlying principle behind many phenomena, such as the propulsion of rockets, the motion of vehicles, and the recoil of firearms.  Understanding and applying this law is crucial in analyzing and predicting the motion of objects in various situations.


Newton's Third Law formula

\(\large{ F_1 = -F_2 }\) 
Symbol English Metric
 \(\large{ F }\) = force  \(\large{lbf}\) \(\large{N}\) 


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Tags: Motion Equations Laws of Physics Laws of Fluid Dynamics