Question

which characteristic does inertia describe? how difficult it is to change an objects motion how long an object is how large an object is how fast an object is moving

Explanation:

Inertia is a property of matter. According to Newton's first law of motion, an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. The more mass an object has, the greater its inertia, and the more difficult it is to change its state of motion (whether it is at rest or moving with a certain velocity). Length, size (volume - related to size in a sense of spatial extent), and speed of an object are not directly what inertia describes. Inertia is specifically about the resistance to change in motion.

Answer:

how difficult it is to change an object's motion