We just learned about the Lug Nut.
Another part of a car is the Rotor, also called the disc.
When the car needs to stop, the rotor is a disc shaped part of the wheel that is spinning around, and the car has brakes that clamp down hard onto the rotors to make it stop spinning and the car slows down and stops.
(from: wikipedia - disc brake)
Kid Facts - Blast from the past: Train Whistle
