1. The problem statement, all variables and given/known data A car rounds a slippery curve. The radius of curvature of the road is R, the banking angle with respect to the horizontal is θ and the coefficient of friction is μ. What is the minimum speed required in order for the car not to slip? 2. Relevant equations Fc = (mv^2) / r W = mg Ffr = μ N 3. The attempt at a solution So I made the xy-plane standard, weight in the negative y-direction. x-direction: Nx + Ffr(x) = Fc N = (mg) / cos (th) Ffr(x) = (μmg) cos (th) / cos (th) = μ mg Nx = [ (mg) sin (th) ] / cos (th) Nx + Ffr(x) = Fc μmg + (mg sin (th))/cos (th) = (mv^2) / r v(min) = sqrt [ gr (μ + tan (th))] That was my answer, but it's not an answer choice. I don't know where my thought proccess was wrong. Can someone help?