The Inertia Frame

An inertial frame is a viewpoint or reference context where objects move in straight lines at constant speeds unless acted upon by forces. Think of it as a "resting" or "constant motion" perspective in which Newton's laws of motion hold true without needing to account for external effects like acceleration or gravity. For example, a spaceship drifting through space at a steady speed with no external forces is an inertial frame. It provides a consistent way to analyze motion because the laws of physics behave predictably in such frames.