Question

If Newton's Third Law of Motion is correct and every action has a reaction which is equal in magnitude but opposite in direction, why don't the action and reaction cancel each other out?

Answer 1

Answer:

Newton's third law: If an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A. ... We sometimes refer to this law loosely as action-reaction, where the force exerted is the action and the force experienced as a consequence is the reaction.

Answer 2

Eg-static equilibrium

Take box on table

Suppose gravity acting on the box towards the table and the table is also applying force back to cancel the downward displacement by upward displacement

And when we apply force on the left side of box the friction from right side makes the force cancel

Hence proved.