How does friction operate in a car when the brakes are applied?

When the brakes are applied in a car, the brake pads come into contact with a disc (or drum, in some systems), generating friction between these two surfaces. This friction is crucial because it is the resistance caused by this interaction that slows the car down. The force of friction opposes the motion of the wheels, thereby converting kinetic energy into thermal energy, which is why the brakes can become hot after extended use.

The effective operation of the braking system relies on the principle that friction can be used to reduce speed or bring a vehicle to a stop, making this a vital aspect of vehicle safety and performance. Without this frictional force, the car would not decelerate effectively, leading to longer stopping distances and potentially dangerous situations. The other options suggest scenarios that do not align with how braking systems function. For instance, the notion that brakes push the car forward or eliminate friction misunderstand the fundamental role of friction in stopping motion.