Final answer:
An object’s resistance to acceleration due to an applied force is called inertia, and it is directly measured by the object’s mass. More mass means more inertia, making it harder to change the object's state of motion.
Step-by-step explanation:
An object’s resistance to acceleration when force is applied is called its inertia. Inertia is essentially the tendency of an object to resist changes in its state of motion, which can be remaining at rest or moving with a constant velocity. The inertia of an object is directly measured by its mass. A larger mass indicates more inertia, making it more challenging to change the object’s motion. Newton's first law, also known as the law of inertia, describes this resistance. Regarding an object's properties, mass is the best quantifier of its inertia, as it indicates how difficult it is to alter its motion when an external force is applied. This should not be confused with weight, which is the force experienced by the mass due to gravity, or with momentum, which is the product of an object's mass and velocity.