Inertia is the natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes the velocity to change. It is one of the fundamental principles in classical physics, and described by Isaac Newton in his first law of motion (also known as The Principle of Inertia).[1] It is one of the primary manifestations of mass, one of the core quantitative properties of physical systems.[2] Newton writes:[3][4][5][6] - Wikipedia