posted by joann .
A banked circular highway curve is designed for traffic moving at 84 km/h. The radius of the curve is 152 m. Traffic is moving along the highway at 43 km/h on a rainy day. What is the minimum coefficient of friction between tires and road that will allow cars to negotiate the turn without sliding off the road?
You have three forces: gravity, friction, and centripetal force.
Break gravity on the car into two components, normal to the surface, and down the surface (parallel).
Now, break centripetal force in to normal, and up the surface (parallel)
Add the up the surfaces (one is negative, weight), and set them equal to friction (mu*sum of parallel forces).