Integrated Science and Technology (ISAT) Exam 3 Practice 2026 - Free ISAT Practice Questions and Study Guide

Newton's first law of motion, often referred to as the law of inertia, states that an object will maintain its state of motion—whether at rest or in uniform motion—unless acted upon by an unbalanced external force. This means that if no net force is applied to an object, it will either stay at rest if it is not moving or continue moving at a constant velocity if it is already in motion.

The selected answer succinctly encapsulates this principle by emphasizing that both an object at rest will remain at rest and an object in motion will remain in motion under the condition that no unbalanced forces are acting on them. This foundational concept in physics lays the groundwork for understanding how forces affect the motion of objects and is crucial to explaining various physical phenomena.

Other options fail to capture the essence of the law correctly. For example, stating that an object in motion requires an external force to stop neglects the concept that it can also be brought to rest by balanced forces acting on it. Similarly, the mention of a balanced force contradicts the law's premise that an unbalanced force is necessary to change the state of motion. The statement about an object in motion eventually stopping without forces overlooks the inherent nature of inertia that dictates it will continue moving unless