In Newton's Third Law, the core idea is that forces come in pairs. When you push a child on a swing with a force of 50 N, this force acts upon the child. This is called the action force. Despite acting in different directions, the reaction force is always equal in magnitude to the action force. This principle is easier to understand through practical examples like pushing on a swing. When such a push occurs, it sets off both action and reaction forces simultaneously.
A visual way to grasp this would be to consider the moment of contact between your hands and the child.
- The moment you apply force on the child through your hands, you have created an action force.
- The child's body will naturally respond with an equal force pushing back on you.
Both of these forces together form the foundational concept of action and reaction forces.