1. The problem statement, all variables and given/known data Assessing the required forces at the top and bottom of a loop de loop. I understand that you need a larger force at the bottom of the loop because you have to counter gravity. My question is, when you are undergoing uniform circular motion and your centripetal acceleration is constant then would your centripetal force also be constant? If you have a loop de loop with a centripetal acceleration of 9.81m/s^2 then at the bottom the reaction force is 2mg which provides the centripetal force but at the top the weight provides the centripetal force which is only mg as the reaction force would be zero. But if v^2/r is constant then how can the centripetal force be different at the top and bottom? 2. Relevant equations F = mv^2/r. 3. The attempt at a solution Have listed my thoughts in the top section.