# Homework Help: A car rounds a banked curve

1. Sep 15, 2010

### KillaKem

I have a physics problem thatz bothering me

A car rounds a banked curve.The radius of curvature = R, bankin' angle a, and coefficient of friction k,.Show that the minimum velocity the car should travel in if it doesn't want to slip down

2. Relevant equations

[ R g * (tan a - k) / (1 + k*tan a) ] ^ 0.5

3. The attempt at a solution

Just give clues don't solve

2. Sep 15, 2010

### PhanthomJay

You shouldn't just use a formula you looked up, right or wrong.....you need to draw a free body diagram and examine all the forces acting on the car. The components of those forces in the horizontal direction provide the centripetal force to keep the car moving in a circle. Note that to determine the max speed, the horizontal component of the friction force points inward, toward the center of the circle. To determine the minimum speed, where the car starts to slip in toward the center of the circle, the friction force horizontal component points outward. Note that in the vertical direction, there is no acceleration.