# Friction of a car going in circles

1. Nov 24, 2008

### Smifsret

1. The problem statement, all variables and given/known data
A car that weighs 900 kilograms is driving around a racetrack, the radius of the racetrack is 100 meters. Thecar has a constant speed of 110 km/h. The friction coefficient between the tires and the track is 0.980.

Decide:

a) The car's acceleration
b) The size of the friction

2. Relevant equations

3. The attempt at a solution

I got a to 9.34 m/s2 which I believe is correct. I'm having a much harder time with b which I get to 8,65 kN which I know is incorrect.

2. Nov 24, 2008

### f(x)

could you show some equations you found

3. Nov 24, 2008

### Smifsret

Ok I tried the Latex thing but I couldn't figure it out so i'll just write normally.

For the acceleration I used a = v2 / r = 30.52 / 100 = 9,34.

The second one is the one I'm sure must be wrong but I don't know what else to try. I'm using the equation for kinetic friction fk=$$\mu$$k*n which should be simply 0.98*900*9.80 =8652.42 = 8.65 kN but that isn't the answer.