Is centrifugal force inertia of motion?

Answer 1

Centrifugal force is an inertial force because it is caused by the rotating frame of reference and not by some external force.

An object on a spinning disk (like a person on a merry-go-round) feels centrifugal force because the merry-go-round is spinning (causing him/her to fly outward on the merry-go-round). There is no external force pushing on the person, they just feel centrifugal force because they are spinning.