Inertia is the tendency of an object to resist changes in its motion. It's directly related to the object's mass - the more massive the object, the harder it is to get it moving or to stop it once it's moving.

Inertia is not affected by force.

Here's why:

* Force causes acceleration: Force is what *changes* the motion of an object. A larger force causes a larger acceleration (change in velocity over time).

* Inertia resists acceleration: Inertia is the property that makes an object resist this change in motion.

* Mass determines inertia: The amount of inertia an object has is determined by its mass. A more massive object has more inertia and resists acceleration more strongly.

In summary: Doubling the force on an object will double its acceleration, but it will not affect its inertia. Inertia remains constant for a given object.