1. The problem statement, all variables and given/known data A car in an amusement park ride rolls without friction around the track shown in the figure (Figure 1) . It starts from rest at point A at a height h above the bottom of the loop. Treat the car as a particle. If the car starts at height h= 5.00 R and the radius is R = 16.0m , compute the speed of the passengers when the car is at point C, which is at the end of a horizontal diameter. 2. Relevant equations Conservation of Energy 3. The attempt at a solution Using conservation of Energy PE_i + KE_i = PE_f + KE_f mgh = mgh + 1/2mv^2 mg(5R) = mg(R) + 1/2mv^2 (We are solving for V, so..) mg(5R) - mg(R) = 1/2mv^2 (Cancel out mass) g(5R) - g(R) = 1/2v^2 2(g(5R) - g(R)) = v^2 sqrt(2(g(5R) - g(R))) = V (Plug in R) sqrt(2(g(80) - g(5))) = V If this is correct so far, is g just gravity or is it centripetal acceleration? I loose confidence at this step..Lead me in the right direction? Thanks!