In lecture 5 of MIT's OCW 8.01 , Prof. Lewin says that when you're in in uniform circular motion, the perceived gravity is always in the opposite direction as the push or pull (so if you're holding onto the end of a rope that's being spun around horziontally, the rope is pulling on you and you feel gravity in the opposite direction). My question is does this perceived gravity have anything to do with Newton's 3rd law? If the rope is pulling on you then you're pulling on the rope as well? And is this 'perceived gravity' due to what's called centrifugal force? How does it work and why does it make you feel as though gravity's pulling on you? Doesn't the centripetal force point inwards?