What does Newton's First Law of Motion state?

Newton's 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 in motion with the same speed and in the same direction unless acted upon by a net external force. This principle emphasizes the concept of inertia, which is the tendency of an object to resist changes in its state of motion.

This law explains that if no net force is applied to an object, it will not change its velocity. For example, a stationary book on a table will not move unless someone applies a force to push or pull it. Similarly, a rolling ball will continue to roll at a constant speed on a frictionless surface indefinitely unless acted upon by a force, such as friction or a barrier.

The other choices reference different laws of motion or principles related to forces and motion but do not represent the First Law. For instance, the statement about equal and opposite reactions pertains to Newton's Third Law, while the idea that acceleration is proportional to net force describes Newton's Second Law. The statement about objects falling at the same rate relates to the effects of gravity and air resistance, not to Newton's First Law.