So I understand that centripetal force is "center-seeking", however I'm curious as to how this looks on a free body diagram. I know there is no arrow on the FBD representing centripetal force. However, if we're looking at say a roller coaster at the top of a loop, gravity points downward, and normal force points downward. So centripetal force would end up being downward. How is it then they the coaster stays against the track? What force is opposing the force due to gravity and the normal force? Also in this particular scenario, what forces would be included in the centripetal force?