# Homework Help: Curve banking problem?

1. Jul 27, 2007

### matibtst

curve banking problem???

1. The problem statement, all variables and given/known data

a curve of radius 30m is banked so that a 950kg car traveling 40 km/h can round it even if the road is so icy that the coefficient of static friction is approximately zero. Find the range of speeds at which a car can travel around this curve without skidding if the coefficient of static friction between the road and the tires is 0.3

2. Relevant equations

This part i really need help in pls may i ask for any equations to use i cant even understand the problem. I can't interpret the free body diagram pls give me a formula ^^

3. The attempt at a solution

none i tried drawing a slope with an object but i don't know how to get the angle of the slope...

2. Jul 27, 2007

### Staff: Mentor

What class are you taking? What equations are introduced in the chapter that this question is from? You need to show more effort before we can help you much.

3. Jul 27, 2007

### ank_gl

when the car has maximum speed, friction is down the slope and when speed is minimum, friction is up the slope

4. Jul 27, 2007

### mgb_phys

First ignore the friction and calculate the slope of he curve from the icy case. Draw a diagram to show the forces on the car.

5. Jul 27, 2007

### matibtst

How do i calculate the slope pls.. i'm taking physics natural science and the last formula our pro gave us was the coefficient of friction times normal force is equal to force of friction. so i don't know how to get the slope of the problem i don't even know how to derive where the slope came from sorry

6. Jul 27, 2007

### mgb_phys

7. Jul 28, 2007

### matibtst

thank you for the diagram it has been very helpful thank you very much i at least have an idea now on how to sole ^^

8. Jul 28, 2007

### mgb_phys

Extending it to the case of friction just involves adding the extra foces, remember that friction will act parrallel to the road in a direction to stop the car slipping.
As you said above, friction force is the normal force * coefficent of friction.

9. Jul 29, 2007

### ank_gl

I guess frictional force considered in this question is the force acting perpendicular to the road which avoids the car slippin towards or away from centre of the circular track(or any kind of track, maybe call it instantaneous center) at lowest and highest speed at the curve respectively.
the frictional force mgb_phys is considering is the force which gets the car going