What does Newton's First Law of Motion state?

Newton's First Law of Motion, often referred to as the law of inertia, articulates that an object at rest will remain at rest, and an object in motion will continue moving at a constant velocity in a straight line, unless acted upon by a net external force. This means that objects have a tendency to maintain their current state of motion.

The correct answer encompasses both aspects of the law: it confirms that not only does an object at rest stay at rest, but also emphasizes that an object in motion will persist in that motion unless influenced by an external force. This concept is foundational in understanding how forces interact with mass and has vast implications in physics and everyday situations.

The other options may partially reflect elements of the law but do not fully capture its comprehensive definition. For instance, while the first choice touches on the persistence of motion, it fails to explicitly mention the state of rest. The second option inaccurately implies that an object at rest can only move when force is applied, ignoring the law's broader context regarding motion. The third option incorrectly asserts that all objects experience equal force in motion, which is not a principle of the First Law. Understanding this law is crucial in grasping the fundamental concepts of motion and force in science.