Answer:
The force of friction between the tires and the road
Explanation:
According to Newton's second law, the net force acting on an object is equal to the product between the object's mass and its acceleration:
[tex]F=ma[/tex]
Where F and a are vectors, so they have a direction. The direction of the net force determines the sign of the acceleration:
- if the net force is in the same direction as the motion, the acceleration is positive --> the object speeds up
- if the net force is in the opposite direction to the motion, the acceleration is negative --> the object slows down
In this case, when the driver applies the breaks, the breaks rub against the tires; the tires stop their motion and therefore they rub against the surface of the road. A net force is cause by this rubbing, and it is called frictional force.
Frictional force acts whenever there are two surfaces in contact with each other, and its direction is always opposite to the motion of the object. In this case, it is the force responsible for the deceleration of the car.
