Ask Dr. Universe – Cars

Dear Dr. Universe: I want to know how my family car works. How does the gas reach the engine and go? How does the steering wheel make the car turn and how do the brakes help us to stop? -Jordan, 6, Queens, New York
Dear Jordan,

As a cat, car rides can sometimes make me feisty. But as a scientist, it’s fascinating to learn about the mechanics, engineering, and chemistry fueling the cars humans drive every day.

First, the gas: Gas is stored in a tank. When a driver pushes down the gas pedal, gasoline flows through a long tube about as wide as a drinking straw, called a fuel line. It works with the fuel pump.

“With more gas running through the fuel line, the engine gets stronger and goes faster,” said my friend Aaron Crandall, an engineer at Washington State University.

A fuel pump can suck a bunch of gas into the line. It’s like what happens when you drink water through a straw. The fuel pump can also push a bunch of gas into a part called the carburetor.

In the carburetor, air mixes with the fuel. It makes a kind of mist, or vapor.

The vapor moves from the carburetor into the cylinders that help the engine create power. Then, spark plugs create a fiery spark in the vapor, which explodes. This reaction makes parts called pistons move up and down, similar to the way our legs do when they pedal a bike. When the piston moves, a crankshaft gets cranking, and the engine starts to work.

Then there’s the steering wheel. How it works depends on how the car is built. In old cars, the steering wheel connects from a pole down to levers. The levers would push rods connected to the wheels. While this made it possible for the car to move in different directions, it was still pretty hard for the driver to turn the steering wheel.

So engineers developed power steering. This kind of steering uses a pump to push fluid around, which helps give the driver extra strength as they turn the wheel, said Crandall.

Lastly, but perhaps most importantly: the brakes.

“Without brakes, driving would be a very scary ordeal,” Crandall said.

He explained most brakes work with friction, like handle brakes on bikes. If you grab the handle on a bike brake, you can see the little brake pads grab the rim of the wheel.

When you push down the brake pedal in a car, it pushes fluid into a piston. This piston forces the brake pad against a brake disk. The disk is connected to the rod between your wheels and when the disk is squeezed, the wheels stop turning. It’s a powerful machine to control with just one foot.

There are thousands of parts that help cars run, Jordan. In ten years, when you get your license, humans will probably have come up with even more creative ways to make cars and zoom around.

Sincerely, Dr. Universe
As Washington State University’s resident science cat and writer, nothing gives my nine lives more meaning than answering kids’ questions.