Final answer:
Newton's First Law of Motion states that a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force. Inertia is the tendency of an object to remain at rest or remain in motion, and it is related to an object's mass.
Step-by-step explanation:
Newton's First Law of Motion states that a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force.
Inertia is the tendency of an object to remain at rest or remain in motion. Inertia is related to an object's mass. Mass is the quantity of matter in a substance.