Reaction force is a fundamental concept in physics, particularly in the study of mechanics. It refers to the force that is exerted by a surface or another object in response to an applied force. According to Newton’s Third Law of Motion, for every action, there is an equal and opposite reaction. This means that whenever an object exerts a force on another object, the second object exerts a force of equal magnitude but in the opposite direction back on the first object.
For example, when a person stands on the ground, their weight exerts a downward force on the Earth due to gravity. In response, the ground exerts an upward force on the person, which is the reaction force. This reaction force is what allows the person to remain standing without sinking into the ground.
Understanding reaction forces is crucial for analyzing how objects interact with one another, whether they are in motion or at rest. It helps explain a variety of everyday phenomena, from walking and driving to complex engineering systems.