Newtons first law of motion, also known as the law of inertia, states that an object at rest will remain at rest, and an object in motion will continue to move at a constant velocity in a straight line unless acted upon by an unbalanced force. This means that if there is no net force acting on an object, then the object will maintain a constant velocity. The law of inertia expresses the natural behavior of a body to move in a straight line at constant speed, and in the absence of outside influences, a bodys motion preserves the status quo. Newtons first law is the foundation of classical mechanics and is essential to understanding the relationship between a physical object and the forces acting upon it.