Cars are automobiles that can transport people. It is the main means of travelling for hundreds of millions of people all over the world. Cars have changed the way we live probably more than any other invention in history. At first only a few people had cars but after a while more and more people bought them because theyimproved the way people lived. Farmers with cars were able to bring their products to places that were farther away. The appearance of cities and towns also changed. More and more workers drove to their jobs and people started to move tosuburbs outside the town centers.

Automobiles give people many jobs. Millions of people around the world work in factories where cars are produced. Millions more work at gas stations, restaurants or motels that travelers stop at.

However, cars also cause problems. Millions of people die in car accidents every year. Automobiles pollute the air that we breathe and parking space in cities is scarce because everyone wants to use their cars to get to city centers.

 

How cars work

Cars are very complicated machines and all systems in them work together. They power a car, control and steer it and make it comfortable for people to drive in.

 

The engine

The heart of every car is its engine. It produces the power that turns the wheels and electricity for lights and other systems.

Most automobiles are powered by an internal combustion engine. Fuel, usually gasoline or petrol, is burned with air to create gases that expand. A spark plug creates a spark that ignites the gas and makes it burn. This energy moves through cylinders in whichpistons slide up and down. They are attached to rods that move a crankshaft. Normal car engines have four to six cylinders but there are also models with eight and sixteen cylinders. The turning movement is passed through the drivetrain to the drive wheels.