1. A roller coaster is designed with a clothoid loop that has a radius of 12 m at the top. For comfort, the apparent weight of a rider at the top of the loop must be 0.400 normal weight. What is the speed of the car at the top of the loop? 2. Fn = 0.400(Fg) Fn = 0.400(mg) mv2 / r = Fn + Fg (Since the Fn and the Fg face the same direction.) 3. The attempt at a solution So my attempt at this was to draw a FBD, and I noticed that the Fn and the Fg face the same direction. From that I could come up with the equation ΞFy = Fn + Fg and then using things I could sub in I came up with; mv2 / r = 0.400(mg) + mg mv2 / 12.0m = 1.400mg v = √((1.400mx9.81m/s2)(12.0m) / m) v = 12.8m/s My question along with if this is correct. Is why is there no force in the positive direction? I understand that the cart is resting on the tracks and is held in there. But shouldn't there be a force going upward? Wondering if someone could explain that and tell me if/where I went wrong.