Flight Safety,. .. .I'll try clear up the centrifugal vs centripetal discussion.. .. .Centrifugal force is felt by someone in the rotating reference frame. The need for a centripetal force is realized in a non-rotating reference frame.. .. .Why can't you measure them both in one frame? Because you can't have a frame that both rotates and doesn't rotate at the same time.. ._________. .I enjoy these kind of discussions, but this stuff isn't opinion. Physics is written down, precise definitions. I'm just echoing what I spent five years studying after high school, with frequent cross checks to my dusty text books to make sure. Granted many physics texts don't explain rotational dynamics very well, but then it's not a simple subject. Do lots of exercises and experiments, study vector calculus and classical mechanics, and five years later it should all come very clear.