What keeps a car stationary when parked on steep hill?

When a car is parked on a steep hill, the force of gravity pulls the car down the hill. To prevent the car from rolling away, the parking brake must be engaged. The parking brake is a mechanical device that locks the rear wheels of the car, preventing them from turning.

The parking brake is typically applied by pulling up on a lever located in the center console of the car. When the lever is pulled up, a cable is engaged that runs to the rear wheels. The cable tightens and locks the brake pads against the brake rotors, preventing the wheels from turning.

In addition to the parking brake, some cars also have a hill-hold feature. The hill-hold feature is an electronic system that automatically applies the brakes when the car is stopped on a hill. The hill-hold feature typically disengages when the driver presses the accelerator pedal.

By using the parking brake and the hill-hold feature, drivers can keep their cars stationary when parked on steep hills.