What are you talking about? Inertia is the tendency of an object to travel in a straight path, thank Sir Newton for that one, drmx is right, inertia is not related to a rotating object at all. Unless, there is a projectile coming off of said rotating object and then we get into tangential velocity and radians and all that fun stuff, and inertia would cause the projectile to fly off in a straight line. Before you answer next time make sure you say something that can't be refuted by a 16 year old high school kid.