One thing to keep in mind is that Newton's Third Law of Motion (N3)
describes a pair of forces acting on two separate objects. A force exerted
by a car door on a passenger sitting tight against the door as the car
travels around a turn, which in the absence of any other forces causing the
person to move in the circle of the turn can be identified as the
centripetal force, is equal and opposite to the force of the person pushing
on the door. Centrifugal force is the pseudo-force that the passenger
"feels." Thus both centripetal and centrifugal forces appear to act on the
same object and are not a pair of N3 described forces.
Richard Bowman
Prof. of Physics
Birdgewater College, Bridgewater, VA, USA