Hi, I have been studying up on circular motion in the vertical plane and I am happy with all the math/theory that I have read explaining the normal force and weight force and the feeling of being "heavier" and "lighter". My question is about the top of the hill/ride, The forces acting on you at the top of the ride are the weight force pulling you down and the normal reaction force pointing up. Obviously the normal reaction force here is smaller and the normal reason given for this is that it needs to be for the net force to be directed to the centre of the circle providing the centripetal acceleration. My question is, what causes the normal to be smaller than the weight force? My understanding is that the centripetal force is the net force resulting from the weight and normal forces so what is it that causes the normal to be smaller than the weight force? Is it to do with the inertia of the car? Any help would be greatly appreciated. Cheers.