1. Nov 4, 2008

### Miss1nik2

On a banked race track, the smallest circular path on which cars can move has a radius of 111 m, while the largest has a radius of 157 m, as the drawing illustrates. The height of the outer wall is 15.7 m. Find (a) the smallest and (b) the largest speed at which cars can move on this track without relying on friction.

I am having trouble finding an answer because I wasnt given any angles. Please help me in any way that you can. Thank you VERY much!

2. Nov 4, 2008

### PhanthomJay

You didn't attach a picture, but I believe that the track is sloped at an angle that has a 15.7m rise over the track width of (157m -111m) = 46m. From that, you should be able to detremine the angle.

3. Nov 4, 2008

### Miss1nik2

Using that information I found the angle to be 18.85 degrees. And I found the answer to part (a) 371.38. But that answer is not correct.

Do you know what I did wrong? Any additional help?? Thank you....

4. Nov 4, 2008

### hage567

Did you remember about the square root?

5. Nov 4, 2008

### PhanthomJay

your angle looks good. I didn't see your work or check out the math on my own, but you may have used the wrong component of net force in the horizontal direction. What did you use, and why?

6. Nov 4, 2008

### Miss1nik2

I used the equation v= sq.rt. r*g*tan (theta)

So, my work for part a is...

sq. rt. (111)(9.8)tan(18.85) = 371.38.

The computer tells me that is the wrong answer...

7. Nov 4, 2008

### PhanthomJay

oh, yeah, should've done the math....take the sq root.....

8. Nov 4, 2008

### Miss1nik2

It worked!!! THANK YOU! I guess I did forget to take the sq rt. Thank you both.