Final answer:
Newton's first law of motion states that an object at rest or moving with constant velocity will remain that way until it is acted on by an outside force.
Step-by-step explanation:
Newton's first law of motion states that an object at rest or moving with constant velocity will remain that way until it is acted on by an outside force. This law is also known as the law of inertia. Inertia is the tendency of an object at rest to remain at rest or, if moving, to remain in motion at constant velocity. Inertia is related to an object's mass.