Finding horizontal force when a car stops in 61 m

[Angeluzmaia]

Help with forces!

I need help with this, I've been trying but I don't understand it. Can anyone help me?

A 830.0 kg car traveling on a level road at 27.0 m/s (60.5 mi/hr) can stop, locking its wheels, in a distance of 61.0 m (200.1 ft). Find the size of the horizontal force which the car applies on the road while stopping.

 

[Pyrrhus]

try $$W = \Delta K$$

 

[Angeluzmaia]

I don't know how is exactly that formula, but I find one, maybe it's the same.

F=m*a

$$a= (v^2-v_{i}^2)/(2* \Delta x)$$


Now I have other problem

Find the stopping distance of that same car when it is traveling up a 19.9° slope, and it locks its wheels while traveling at 33.5 m/s (75.0 mi/hr). Assume that $$\mu_k$$ does not depend on the speed.

 

[Angeluzmaia]

please help me, this is urgent...
Any formulas will be helpful

 

[arildno]

1. What's the normal force exerted on the ground upon the car?
2. How is the magnitude of frictional force related to the magnitude of the normal force?