🚗 Cars and roads

A traffic light has three colours: red, yellow, and green. Each colour tells cars what to do.

Wheels let a car roll smoothly along the ground instead of dragging and scraping like a heavy box would, which means the car needs far less push or pull to move forward. A round wheel touches the ground at just one small spot at a time, so there is much less rubbing and resistance holding the car back compared to sliding flat on the road. Wheels also spin freely on an axle, which lets the engine's spinning power turn into the car actually moving forward down the road.

A car horn makes a loud beep, beep sound. Drivers use it to say watch out.

A car's engine needs energy to spin its wheels, and that energy comes from somewhere, either burning fuel like petrol inside the engine, or electricity stored in a battery for electric cars. Burning fuel releases a burst of energy that pushes tiny parts inside the engine, which then turns the wheels, while an electric motor uses electricity directly to spin without any burning at all. Without fuel or a charged battery, a car's engine simply has no energy to work with, which is why a car cannot move at all once it runs completely out.

When a car suddenly stops or crashes, everything inside keeps moving forward at the same speed the car was going, including you, unless something holds you back safely. A seatbelt stretches across your body and locks tight the instant it senses sudden movement, spreading the force of a stop across your stronger bones instead of just your softer body parts. Wearing a seatbelt correctly, snug and low across your hips, can be the difference between a small bump and a serious injury during a sudden stop.

A seatbelt keeps you safe in your seat when the car stops or turns.

Cars come in many colours, like red, blue, white, and yellow.

A red light means stop completely and wait, a green light means it is safe to go, and a yellow or amber light means the light is about to change, so drivers should slow down and prepare to stop. Traffic lights let cars coming from different directions take turns safely crossing a busy intersection, instead of everyone trying to cross at exactly the same time. These colours were chosen partly because red is easy to notice quickly, even from far away or in bad weather, which helps drivers react in time.