Kids are filled with endless questions that sputter out at incredible speeds and during the strangest of times. Going anywhere is an adventure for them — except maybe the dentist. While roadtripping for the summer, you can look forward to all kinds of questions that require explanations about what is gas, what is oil, how the engine works and more. 

It’s “Why is the sky blue?” all over again except with mechanical whirligigs and gears — and science! Here’s what you need to know and how to explain gas, of the car variety, to your kids while on the road.

A General History of Cars

Most people think of the Ford Model T car from the early 1900s as the first car, but people tried to build cars based on steam as early as the 1770s. 

If your kid loves trains, this is a great hook to lead with — some even moved by themselves as fire pumpers. A hundred years later, Europeans were still trying to create a vehicle for everyday use with mixed results, and they were fueled by steam, gas or electricity. As of the 1890s, people in Europe and the United States were buying cars and driving them, but gas-powered vehicles became the most popular by the turn of the century. 

How did the different types of fuel make the cars move? Steam cars burned fuel which heated water inside a boiler to create steam. The steam expanded, pushing pistons and turning a crankshaft. Electric cars contained a battery powering a small motor which pushed a drive shaft. It is important to know that drive shaft phasing is the correct alignment between yokes at each end of the shaft. Gasoline cars ignited fuel, causing a tiny explosion in each cylinder to push a piston and turn the crankshaft linked to the wheels by a drive shaft or chain. 
So what’s with the Ford Model T? Many bought earlier cars as a status symbol, but the Ford Model T was more sturdy, practical and affordable compared to the rest, so it gained in popularity. Gas was more economical and the energy from the gas and the engine took the car farther. Soon, more people drove, and today, it’s a convenient, comfortable and highly popular means of getting around — though the environmental impact raises concerns. 

How Oil and Engines Go Together

You put gas, which is made from oil, in your car to keep it running. The U.S. uses an average of 19 million barrels of oil a day, and oil is older than you think, because it takes millions of years to form. The process began 551 to 252 million years ago during the Paleozoic Age, in which 10 percent of oil existing today was created. But 70 percent of oil formed during the Mesozoic Age, since there was more plankton in the ocean. This process leads to the creation of oil. 

Oil is formed by dead organic matter mixing with clay-like material on the ocean floor to produce a rich mud which is covered by more sediment to create a rock called "shale" underneath. Buried miles deep in the Earth, temperature increases and the shale gets transformed into kerogen. When kerogen temperatures are between 90° C and 160° C, kerogen forms oil and natural gas — but natural gas can also form at slightly higher temperatures. 

Both oil and natural gas are made up of carbon and hydrogen, and methane is the simplest hydrocarbon. Researchers were aware of these hydrocarbons but couldn’t get to them, so gas was ignored at first. Natural gas differs from oil by just a few added ingredients and molecules.

Petroleum is the liquid that comes from oil that goes in cars, and it literally means “rock oil.” Petroleum didn’t become important for driving until the first internal combustion engine was developed by Nikolaus Otto in 1863. Otto's engine produced heat by igniting fumes derived from a petroleum liquid. The heat pressure moved the pistons to move the car. This is still the basic formula for how engines work today.

How Does an Engine Work Today? 

You get the energy to make the car move by burning the hydrocarbons inside the oil and natural gas. When those hydrocarbons are burned in air, their molecules split and combine with oxygen to create water and carbon dioxide gas. The energy therein gets released as heat. This entire process is called "combustion" — and it involves releasing large amounts of energy to make the car go. 

People have made energy by burning hydrocarbons for ages, such as starting a campfire for cooking. Regular fires waste energy, but car engines are very efficient because the energy goes into closed containers — or cylinders inside the car's engine. Does your car have four, six or eight cylinders? The heat energy gets captured as the fuel releases, creating mechanical energy that impels the car to move.

On top of each cylinder, valves act as gates to let fuel and air enter from an electric fuel-injector or carburetor and exhaust escape. A spark plug on top of the cylinder lights the fuel. The piston on the bottom of the cylinder is attached to a constantly-rotating axle known as a "crankshaft." This crankshaft powers the gearbox, and the gearbox in turn moves the wheels.

Go, go, go! If you're roadtripping to a campsite, you can also explain while starting a fire that the body absorbs the energy produced by the fire as well — so humans have their own “engines,” too, in a manner of speaking. But that’s another topic for another day.