1. The problem statement, all variables and given/known data An air race pilot with 54 kg makes a vertical loop with 1200 m of radius, in such a way that the airplane's speed decreases at a constant rate. Knowing that the airplane's seat force acting over the pilot is 1680 N at point A and 350 N at point C, determine the airplane's seat force when the airplane is at point B. 2. Relevant equations 3. The attempt at a solution There are three forces acting over the object: the weight W, the centripetal force Fc and the airplane's seat force F. I suppose at point A it's something like this: [tex] F_c - W - F_a = 0 [/tex] and at point C: [tex] F_a - W - F_c = 0 [/tex] I'm not really sure if these equations are correct. Substituting what I know I can get the speed at that points. But what should I do then to find the force acting at point B?