# Banked Curve Simple Conceptual Problem

1. Nov 29, 2009

### Fireworks

1. The problem statement, all variables and given/known data
Curve on highway, 15 degrees, designed for 85 km/h and car goes 110 km/hr. Horizontal component of normal force on car is:

a. in same direction as the centrifugal force
b. parallel to the road and towards the inside of the curve
c. in the same direction as the normal force
d. parallel to the road and towards the outside of the curve

2. Relevant equations
Conceptual problem

3. The attempt at a solution
I believe the answer is C, but I have to justify my answer and don't fully understand it. I think the horizontal component and the centripetal force point down the curve, but I am not completely sure.

2. Nov 29, 2009

### PhanthomJay

Centripetal force always points inward toward the center of curvature of the path. Are there more choices? Choice 'c.' is not correct.

3. Nov 29, 2009

### Fireworks

I mistyped the answers, answer c is supposed to be: in the same direction as the centripetal force. And that is what I think it should be, but.. still could use some explanation help.

4. Nov 29, 2009

### PhanthomJay

Yes, C is correct, this figure should help:

http://hyperphysics.phy-astr.gsu.edu/HBASE/mechanics/carbank.html#c1

Any mass not moving in a straight line is centripetaly accelerated inward toward the center of the path of curvature, a_c = v^2/r, giving rise to a centripetal force in that direction, per Newton's 2nd Law, F_c =mv^2/r. This is true even if the speed of the object along the curved path is not constant.