According to Newton's third law of motion, for every action, there is an equal and opposite reaction. This means that forces always occur in pairs. When one object exerts a force (the action) on a second object, the second object simultaneously exerts a force of equal magnitude in the opposite direction (the reaction) on the first object.
For example, if you push against a wall, the wall exerts an equal and opposite force back on you. If a rocket propels itself forward by expelling exhaust gases backward, the action of the gases moving one way results in a reaction that propels the rocket in the opposite direction.
The key points about action and reaction forces are:
- They act on two different objects.
- They are equal in magnitude but opposite in direction.
- They do not cancel each other out because they are acting on different bodies.
This principle is fundamental in understanding interactions in physics, from simple daily occurrences to complex mechanical systems.