# Centripetal Force: Banked Curve

## Homework Statement

A 1200 kg car travels around a curve banked at 42.5 degrees in a circular path of radius = 150m, but the ramp is only 55m long. The force of friction on the car is 9000N, calculate the speed of the car.

So:

radius = 150 m
θ (angle the incline makes with the horizontal) = 42.5
mass = 1200 kg
Friction = 9000 N

Fc= FNx + FFx

Fc= mv2 / r

## The Attempt at a Solution

The car does not move in the y-plane, therefore:

Ff + Fg + FN = 0

FN = (mg + Ffsinθ)/cosθ

Solve for FN and I got 24213.83512 N

Then I used the value of FN to find FNx and added FFx to it.

Then I multiplied by the radius, divided by the mass and took the square root leaving me with 54m/s.

However, when I use the formula found on this page http://en.wikipedia.org/wiki/Banked_turn" [Broken] I got 67 m/s.

Which one is right? And If I'm wrong, where did I go wrong?

Last edited by a moderator:

## Answers and Replies

How did you apply the 9000N to the equations on the Wiki site?