A banked circular highway curve is designed for traffic moving at 60km/h. The radius of the curve is 200m. Traffic is moving along the highway at 40km/h on a rainy day. What is the minimum coeficient of friction between tires and road that will alow cars to take the turn without sliding off the road? (assume the cars do not have negative lift.) I have a feeling Centripetal force is involved, but it gives no mass of a vehicle. I m pretty much lost, could someone point me in the right direction please!