- #1

badsniper

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## 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

## Homework Equations

F

_{c}= F

_{Nx}+ F

_{Fx}

F

_{c}= mv

^{2}/ r

## The Attempt at a Solution

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

F

_{f}+ F

_{g}+ F

_{N}= 0

F

_{N}= (mg + F

_{f}sinθ)/cosθ

Solve for F

_{N}and I got 24213.83512 N

Then I used the value of F

_{N}to find F

_{Nx}and added F

_{Fx}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?

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