How does the force of friction for a sliding object vary with the area of contact?

The force and texture of an object matter a lot.

Explanation:

If you were to try and run up a glass hill, could you? You maybe could, but it would be harder to than up carpet.

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

e) none of the above answers are correct