Lu,
Sir Isaac Newton was a clever chap, he realised that an object will remain in linear motion unless acted upon by a FORCE which would change its velocity. He also realised that a FORCE would be accompanied by an equal and opposite reaction. That reaction is not a force otherwise you would have 2 opposing forces and so no work would be done and nothing would happen. A blade being rotated is experiencing a FORCE which acts toward the centre of the hub - a centripetal force (centripetal meaning acting toward the centre). This radial FORCE causes an acceleration toward the centre of the hub. If that acceleration were not there the blade would fly in a straight line and upset some poor pilots otherwise tranquil day. This is BASIC Newtonian physics, I studied it at school. Now to simplify the understanding of such things non-technical or lower level descriptions of rotating systems call the inertial effects described by Newtonian physics "Centrifugal Force" because is is a difficult concept to grasp. Thankyou Lu for your fine demonstration of someone who can't grasp Newtons Laws of motion. I shall continue in my blind faith in published experts and Nobel laureates over blockheadedness and simplicity.
