Alright so I need some help

were doing Friction and Centripetal Force

A 1250 Kg car traveling at 12 m/s is exiting circular highway exit ramp with a radius of 36 meters

then I'm asked to find the acceleration
the centripetal force
the normal foce
which I have done then I'm asked to

calculate the minimum value of the coefficient of friction necessary for the car to stay on the road...

I have no idea how to do this...
I now that Ff= uFn I think or something like that so I don't know how to do this problem because well I know the Fn but not the Ff or do I???

please show me all the formulas you use and step by step thanks

Here is what I suggest. Go immediately to BarnesNoble, or your local college bookstore, and take a look at Schaumn's Outline Series, College Physics (there are several versions, I like the physics for engineers).

It has many solved problems that will guide you through the process. It is relatively inexpensive.

To solve this problem, we can use the equations related to circular motion and the concept of friction.

First, let's find the acceleration of the car as it exits the circular highway ramp. The formula for centripetal acceleration is:

a = v^2 / r

where:
a = acceleration
v = velocity
r = radius

Plugging in the given values, we have:

a = (12 m/s)^2 / 36 m

a = 4 m/s^2

Next, let's calculate the centripetal force acting on the car. The formula for centripetal force is:

Fc = m * a

where:
Fc = centripetal force
m = mass
a = acceleration

Plugging in the given values, we have:

Fc = 1250 kg * 4 m/s^2

Fc = 5000 N

Now, we need to determine the minimum value of the coefficient of friction necessary for the car to stay on the road. In this situation, the friction force provides the necessary centripetal force to keep the car on the circular path. The maximum friction force (Ff) can be calculated using the equation:

Ff = μ * Fn

where:
Ff = friction force
μ = coefficient of friction
Fn = normal force

To find the normal force, Fn, we need to consider the forces acting on the car. The normal force is equal to the weight of the car if it is not accelerating vertically. Therefore:

Fn = mg

where:
m = mass
g = acceleration due to gravity (approximated as 9.8 m/s^2)

Plugging in the given values, we have:

Fn = 1250 kg * 9.8 m/s^2

Fn = 12250 N

Now, to calculate the minimum coefficient of friction, we can set up the equation:

Fc = Ff

1250 kg * 4 m/s^2 = μ * 12250 N

Solving for μ, we find:

μ = (1250 kg * 4 m/s^2) / 12250 N

μ ≈ 0.408

Therefore, the minimum coefficient of friction necessary for the car to stay on the road is approximately 0.408.

Remember to always double-check the units and pay attention to significant figures throughout the calculations.