I'm having trouble with circular motion, for the simple reason that my instructor taught it differently than my book explains and how I see it done online. He explains that centripetal force moves towards the outside of the circle, and is an independent force. Meaning, he explains it as a force that maintains and is caused by circular motion. For instance, if I were swinging a ball on a rope horizontally, he would say that F=T-Fc, that the sum of the forces are centripetal force and tension acting in opposite directions (tension toward the center, centripetal force toward the outside). Now, I'm seeing it online that Fc=T because tension is the net force that maintains circular motion, and centripetal force and tension are one and the same. Algebraically, that makes sense, and both still produce the correct solution, but I'm wondering, why would my teacher teach that concept incorrectly? Is that a valid method or is he just an idiot? I need some help because I'm pretty confused. Also, as a side note, I was wondering what the centripetal force was on a rotating object, such as a merry-go-round or a turntable, because I really have no idea.