You wait in line, your excitement building. Finally, you take a seat. Your heart pounds as a safety bar locks around you. Suddenly—WHOOSH! Your seat shoots forward. You’re off on a record-breaking roller coaster ride!

That’s the idea behind Maxx Force, a new coaster opening this summer at Six Flags Great America in Illinois. Maxx Force will launch riders from 0 to 126 kilometers (78 miles) per hour in just two seconds. That’s the fastest start of any coaster in North America!

It takes a team of engineers to build a roller coaster like Maxx Force. One of them is Lee Stellhorn. He’s been designing rides at Six Flags for more than 20 years. It’s Stellhorn’s job to harness the forces that affect passengers during their ride. “You need to understand physics to create a ride that’s both fun and safe,” he says.

The Need for Speed

People have been seeking out thrilling rides for hundreds of years. In the 1600s, people in Russia built ice-covered ramps up to 21 meters (69 feet) tall. They pushed sleds to the top. Then the force of Earth’s gravity sped them down the hill.

Over time, engineers replaced the sleds with wheeled carts. A second set of wheels attached from below kept the cars from veering off the tracks. 

In 1884, one of the first roller coasters, called the Gravity Pleasure Switchback Railway, opened in New York City. Passengers coasted along a hilly wooden track. The ride was a hit, even though it reached just 10 kilometers (6 miles) per hour—about as fast as a jogging pace. Engineers have been making coasters faster, taller, and more exciting ever since.

Wild Rides

Modern steel tracks allow engineers to build much more complicated coasters. But the basic principles have not changed. Engineers rely on gravity to keep cars moving.

Today, most coasters use a motorized cable to pull cars up the first hill. On other rides, like Maxx Force, a blast of compressed air launches cars to the top (see Design of Maxx Force). The cars gain potential energy as they rise. The taller the hill, the more energy they have.

As riders tip downward, gravity takes over. The cars gain speed, as well as kinetic energy, as they zoom down the track.

Turning up the next hill, riders can feel the acceleration, says Becky Thompson. She’s a scientist at the American Physical Society—and a roller coaster fan. According to Thompson, you may even feel like you’re leaving your guts behind. “Your stomach wants to continue down,” she says, “but the force of the track is saying ‘Nope, we’re going up!’”

Smooth Moves

To design a new coaster, engineers like Stellhorn plot out the track on a computer. That helps them plan the shape they want it to be.

Once a coaster is built, engineers test it to make sure it’s safe. They fill plastic dummies with water to mimic the weight of riders and load them onto the ride. Seeing how the dummies move allows engineers to fix problems before real people take a turn.

Engineers began building Maxx Force this past fall. If the towering coaster passes all of its tests, Stellhorn will be one of its first riders. It will open to the public after that. “I get to do things daily that we charge people to do at our parks,” says Stellhorn. “It’s such a fun career.”