1. The problem statement, all variables and given/known data http://img39.imageshack.us/img39/3778/funkyrider.jpg [Broken] So I got this funky rider that starts its movement from the top of the hill A at initial speed (Vo). From that point, the bicycles role on freely (without using pedals) at the circular path. Calculate the velocity of the rider at the bottom point B. W= (weight of the rider+bicycle) = 650 [N] Vo (initial velocity) = 27 km/h H = 14m R= 10m Comment: Ignore friction C is point mass 3. The attempt at a solution HERE is my problem. Last year in my notebook I wrote this: http://img204.imageshack.us/img204/6220/vfold.jpg [Broken] I tried resolving it but I didn't get the same result. This result is the same one in the manual so I reckon it's correct. I tried a = -9.81 a = 9.81 a = v2/R = 7.52/10 a = g2/R = 9.812/2 Nothing works. The third one makes slight sense to me because according to the formula of circular motion that's what "a" ought to be, v2/R...problem is that using this I'm not considering "g" and that's impossible, therefor the last a makes most sense to me. None of them gives me my old answer!