# Speed of car on a curve bank?

1. Oct 24, 2013

### jimmyboykun

1. The problem statement, all variables and given/known data
On a highway curve with radius 55m, the maximum force of static friction that can act on a 795kg car going around the curve is 8740N. What speed limit should be posted for the curve so that cars can negotiate is safely?

2. Relevant equations
ƩF=ma, a=v^2/r

3. The attempt at a solution

8740N=795kg(v^2/55m)

8740N= 4375m*kg(v^2)

0.200m/s= v^2

v=0.144m/s

it looks like I performed my math correctly, but I need a second opinion. The solution that I solved does not appear in the answer choices of my practice exam.

2. Oct 24, 2013

### jimmyboykun

A) 241.23m/s
B)10.99m/s
C)7798.95m/s
D)604.65m/s
E)24.59m/s

3. Oct 25, 2013

### Mentz114

It is D)

m v2 / r = F

v = √(98740.55/795) = 604.65408805031446540880503144654

4. Oct 26, 2013

### jimmyboykun

thanks, but where did I go wrong with my math? everytime I isolate v I get letter E

5. Oct 26, 2013

### jimmyboykun

Thanks, but I believe the velocity that you gave did not work, :( 11.14 would be the velocity.

Here's what I did, 8740N*55/795 = v^2

v = 24.59m/s