Final answer:
The block brake primarily functions to stop motion by using friction to reduce speed and transform motion energy into heat energy.
Step-by-step explanation:
The block brake primarily functions to stop motion.
The brakes on cars use friction to reduce speed and transform motion energy into heat energy. When the car brakes, the friction between the brake pad and the wheel slows down the car, converting its motion energy into heat energy. This is why the brakes of a car can become very hot after bringing the car to a stop.