# Required frictional force for a car to keep it from sliding off a curve.

1. Nov 11, 2007

### galuda

1. The problem statement, all variables and given/known data
With what frictional force must the road push on a 1200 kg car if the driver exceeds the speed for which the curve was designed by deltav = 14km/hr?

3. The attempt at a solution
I actually have no clue where to begin with this question. Don't I need the radius to figure this out? On the previous problem i was asked to find the bank angle of a curve given radius and velocity and I used tan-1 [v^2/(gr)]. I don't believe that equation is relavent here though. Any advice as to what equations I should be using?

Last edited: Nov 11, 2007
2. Nov 11, 2007

### suspenc3

Is that exactly how the question is written? It seems kinda confusing

3. Nov 11, 2007

### galuda

Yup, that's all it says, other than answer in units of N at the end. Doesn't even say if it's a flat curve or banked.

4. Nov 11, 2007

### galuda

Now the question doesn't say to refer to the previous problem, but if it does it was If r = 51 m and v = 52 km/hr, what is theta? and i found that to be 22.646 degrees. Can we do anything with that information?

5. Nov 11, 2007

### galuda

AHAH! Well I decided to use the degree, radius and velocity from the previous 2 problems, found my force of the original speed that required no friction, added 14km/hr to it and found that force, then subtracted one from the other and that answer was correct. Would have been a whole lot simpler if they had just said "refer to the previous 2 problems to solve this one". Thanks anyways!