Defining equation (physics)

In physics, a "defining equation" typically refers to a fundamental equation that describes the relationship between key physical quantities in a particular context. These equations derive from physical laws and principles and are used to define specific phenomena or systems. For example: 1. **Newton's Second Law**: \( F = ma \) (where \( F \) is force, \( m \) is mass, and \( a \) is acceleration) is a defining equation for classical mechanics.