Final answer:
To have an object gain more inertia, you need to increase its mass. Inertia determines how much resistance an object has to changes in its state of motion, and mass is directly proportional to inertia.
Step-by-step explanation:
In order to have an object gain more inertia, you can increase its mass. Inertia is a property of matter that quantifies the resistance of an object to changes in its state of motion. The more mass an object has, the greater its inertia, and thus, the harder it is to change its motion whether you are starting it moving, stopping it, or changing its direction. For example, a heavy crate requires more force to push across a concrete floor and start moving than a lighter crate due to its greater inertia. Once it is moving, it's also harder to stop for the same reason. Even in the case of a rotating system, such as a merry-go-round, the further the mass is distributed from the centre, the greater the moment of inertia and the harder it is to change its rotational speed.