Friction question (intro level)

[Fallinleave]

A banked circular highway curve is designed for traffic moving at 55 km/h. The radius of the curve is 213 m. Traffic is moving along the highway at 49 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?

I found the angle to be 6.38 degree. Is it right? How do I go from here?
Thanks,

 

[collinsmark]

I found the angle to be 6.38 degree. Is it right?

That's pretty close to what I came up with, differing by only the 3rd significant digit.

How do I go from here?
Thanks,

A free body diagram (FBD) would be a good start. Your FBD should look pretty similar to the FBD in the first part, except there is now a frictional force involved, parallel to the surface of the road.

(Then prepare yourself for bit of algebra). http://www.websmileys.com/sm/cool/694.gif