What is Newton's First Law of Motion?

Newton's First Law of Motion states that every body continues in its state of rest or uniform motion unless acted upon by an external force. This principle emphasizes the concept of inertia, which is the tendency of objects to resist changes in their state of motion. If no net force is applied to an object, it will either remain at rest or continue to move at a constant velocity in a straight line.

This law lays the foundation for understanding motion and is crucial for analyzing the behavior of objects in various scenarios, especially in aviation where changes in speed and direction need to be managed considering all acting forces, such as thrust, drag, and gravity. The idea that an object will not change its motion unless influenced by an external force helps explain how aircraft maintain their flight path until pilots or automatic systems apply control inputs.

In contrast, the other principles listed define different aspects of motion and force. The concept of an action-reaction pair is articulated in another of Newton's laws, specifically the Third Law. The Second Law, expressed as force equals mass times acceleration, relates force to an object's motion but does not describe its persistence or resistance to motion changes as directly as the First Law does.