1. The problem statement, all variables and given/known data A roller coaster loop has a radius of 12m. If the passengers in a car are not to fall out at the top of the loop, what is the minimum speed the car must have at the top? 3. The attempt at a solution Alright I think I got the right answer but I do not completly understand the question. so what i did was I went Fc=Fg (but why??) g is 9.8 mg=mv^2/r g=v^2/r v=11 But I dont get why the MINIMUM ac has to be g for them not to fall off.