Which property of matter is defined as the tendency of an object to resist changes in its state of motion?

• A. Inertia
• B. Friction
• C. Mass
• D. Acceleration

Answer: (A)

Inertia is the property of matter that describes an object's resistance to changes in its state of motion. This concept is rooted in Newton’s First Law of Motion, which states that an object at rest will stay at rest, and an object in motion will stay in motion at a constant velocity unless acted upon by an unbalanced force. Therefore, inertia is fundamentally linked to mass—the greater the mass of an object, the greater its inertia, making it harder to start moving or to stop moving once it is in motion.

Friction is a force that opposes motion when two surfaces are in contact, and it's not a property that defines an object's tendency to maintain its motion. Mass refers to the quantity of matter in an object and is a factor that influences inertia, but it doesn't define the tendency itself. Acceleration pertains to the change in velocity of an object over time, which is the result of unbalanced forces acting on it, rather than a property of matter that resists changes in motion.

Thus, inertia is the correct choice as it encapsulates the idea of an object maintaining its state of motion unless interfered with by an external force.