Answer:
When a car brakes, it experiences a forward deceleration force, which is generated by the braking system. This force acts in the opposite direction to the car's motion and causes the car to slow down. As a result of this force, the horizontal forces acting on the car change.
When the brake is applied, the friction between the brake pads and the rotors generates a braking force that acts on the wheels. This force causes the wheels to slow down and, as a result, the car's forward motion is slowed down as well.
At the same time, the car's weight shifts forward, causing a decrease in the vertical force acting on the rear wheels and an increase in the vertical force acting on the front wheels. This increase in the front wheel's vertical force creates more friction between the tires and the road, which in turn generates a larger horizontal force that acts to slow down the car.
Additionally, as the car slows down, the aerodynamic drag acting on the car decreases, resulting in a smaller horizontal force acting on the car. However, the net effect of all these changes is a decrease in the car's forward motion and a corresponding decrease in the horizontal forces acting on the car.