Why is mass used to represent inertia?

Answer 1

Because after much investigation, experiment, and experience, in laboratories

of Physics all over the world, it has been determined that there is more inertia

where there is more mass, and less inertia where there is less mass. Moreover,

through careful measurement, it has been possible to quantify the relationship,

and to demonstrate, analytically and conclusively, that intertia is precisely and

directly proportional to mass, and that where there is no mass, inertia is zero.

Be that as it may, and when all is said and done, it became clear that mass is

like unto no other quantity as a worthy and proper surrogate for inertia.

Answer 2

Mass is used to represent inertia because mass quantifies the amount of matter in an object, which ultimately determines how resistant an object is to changes in its state of motion. Inertia describes an object's tendency to maintain its current state of motion, and mass serves as a measure of this tendency. Objects with greater mass have greater inertia, making them harder to accelerate or decelerate.