Final answer:
Mass is the physical quantity that measures an object's inertia, which is the resistance to changes in motion. Unlike volume or density, mass does not change with the object's location.
Step-by-step explanation:
The physical quantity that measures an object's inertia is its mass. Inertia is an object's resistance to changes in its state of motion. Mass is a measure of the amount of matter in an object and is independent of the object's location.
This means that an object's mass is the same on Earth, in orbit, or on the surface of the Moon. Volume and density are different properties; volume is the measure of the space an object occupies, and density is the mass per unit volume. When comparing the inertia of two objects, the one with greater mass will have more inertia and be more resistant to changes in its motion.