We express the braking force from relation (9): \[Fb = {m*v_0^2\over 2*Ss}\]
Note: The kinetic energy of a car at the beginning of its brakins is qual to the work done by the braking force: W=Ek
\[Fb = {f*N = f*m*g}\]
Fb..frictional braking force
f..coeficient of static friction
N..force wich the car acts upon the road
m..the mass of the object
g..the acceleration of gravity
The coefficient of friction f will be the sabe in both scenarios
We substitute for Fb from relation (10)
Fg.. gravitational force
N1..normal force with which the road upon the car
Fb1..braking force
\[Fb_1 + Fg + N_1 = {m * a_1}\]
We rewrite the equation using scalars and choose a coordinate system such that the x axis is parallel to the movement of the car.
The y axis is perpendicular to the x axis. We split the gravitational force into two components in the directions of the axes: