About centrifugal force, allow me to post onece more. A disk and the same ten spheres (evenly spaced around the disk) are rotating on a plane (no friction). Spheres and outer edge of the disk are connected with strings of the same length. Each string will show the same tension. Tension will be a sign that centrifugal force is not fictitious.
Note) Centrifugal force and centripetal force will work on the string (on every point) as Newton's third law of motion.
