# Uniform Circular Motion Problem

1. Oct 2, 2009

### Gattz

1. The problem statement, all variables and given/known data
A circular curve of highway is designed for traffic moving at 93 km/h. Assume the traffic consists of cars without negative lift. (a) If the radius of the curve is 210 m, what is the correct angle of banking of the road? (b) If the curve were not banked, what would be the minimum coefficient of friction between tires and road that would keep traffic from skidding out of the turn when traveling at 93 km/h?

2. Relevant equations

a=v2/r

3. The attempt at a solution
I found acceleration to be 3.177 m/s2. Then I tried setting ma to Fnradial, which I got to be mgcostheta * mgsintheta. But there are two thetas.

2. Oct 2, 2009

### defunc

Wheres the cosine coming from? I think the correct equation should be ma=mgsin(theta)

3. Oct 2, 2009

### planck42

Before trying to directly calculate centripetal acceleration, ask yourself about the forces that act on a car in motion on a banked curve.