# Banked Curve Impossible Problem

1. Oct 20, 2013

### physicsnobrain

1. The problem statement, all variables and given/known data
A curve of radius 67 m is banked for a design speed of 95 km/h. If the coefficient of
static friction is 0.30 (wet pavement), at what range of speeds can a car safely handle the
curve?

2. Relevant equations

I drew this freebody diagram.

3. The attempt at a solution
I have no clue how to do this.

Anyways, on the range of speeds there is a minimum speed and a maximum speed.

For the minimum speed friction has act enough that the car doesn't slip off the hill? I think, again I have no ****ing clue.

For the maximum speed friction has to be enough so the car doesnt fly off the curve. I think

Anyways we probably have to solve for some angle, but I have no clue where or how this happens.

Fnet is not existant here?

anyways, All I have done is convert 95kmh to m/s which is 26.388m/s.

SO nobody knows how to solve this question? It is ranked as one of the world's hardest problems.

2. Oct 20, 2013

### Zondrina

I think you're over exaggerating the problem a bit.

Inclined edges add a force that keeps the car on its proper path as it circles a banked turn. This force is the horizontal component of the car’s normal force. It along with the static force of friction create the force required for centripetal acceleration and ensures the car does not fly off the ramp.

3. Oct 21, 2013

### physicsnobrain

Yea all those equations dont make no sense if you dont have the angle. Which they forgot to tell me in the question

4. Oct 21, 2013

### Zondrina

Indeed, the question is flawed.

5. Oct 21, 2013

### physicsnobrain

unfortunately I still have to solve it so I don't get a zero. Thanks for the help anyways.

6. Oct 21, 2013

### ehild

You can find the banking angle from the first sentence of the problem. It means that the cars ravelling with 95 km/h can do the curve even with zero friction. What is the angle then??

ehild