Speed Racer

Aurora competes in professional road racing. In her sport, each track has its own unique set of twists and turns—any of which could send her flying into the wall if not navigated correctly. That’s because as a car heads into a turn, inertia—an object’s tendency to resist change in its motion—would keep it barreling straight ahead. Luckily, as a driver steers around a curve, centripetal force pulls the car toward the inside of the turn, helping the car follow a curved path instead.

Centripetal force experienced by a race car comes from its tires gripping the track as they turn. But if the car takes a turn too sharply, its weight shifts, causing the outside tires to lose their grip. “[The car] is not getting the force to pull it toward the center of that turn, and it will skid to the outside,” says physicist Stephen Granade.

Aurora’s sport is professional road racing. Each track has a different set of twists and turns. Those turns could send her flying into the wall if she doesn’t handle them well. That’s because of inertia—an object’s tendency to resist change in its motion. When a car heads into a turn, inertia would keep it moving straight ahead. But centripetal force helps pull the car toward the inside of the turn as a driver steers around a curve. So the car follows a curved path instead.

Centripetal force on a race car comes from its tires. They grip the track as they turn. But if the car takes a turn too sharply, its weight shifts. That causes the outside tires to lose their grip. “[The car] is not getting the force to pull it toward the center of that turn, and it will skid to the outside,” says physicist Stephen Granade.

To increase grip, the back of Aurora’s race car is outfitted with a device called a spoiler, which Granade likens to an upside-down wing. An airplane wing’s shape allows air to flow faster over the wing than under it. That creates lift, a force that pulls the plane upward. “You flip that effect over for cars because you don’t want them to lift up,” says Granade. Instead, airflow around the spoiler generates downforce that presses the car against the track.

The back of Aurora’s race car has a device called a spoiler. This helps increase grip. Granade says a spoiler acts like an upside-down wing. An airplane wing’s shape allows air to flow faster over the wing than under it. That creates lift, a force that pulls the plane upward. “You flip that effect over for cars because you don’t want them to lift up,” says Granade. Instead, air flows around the spoiler to create downforce. This presses the car against the track.

Aurora takes into account all the ways these forces can affect her performance. Weeks before a race, she uses a computer program to solve equations that calculate the fastest possible speed for her car on each turn. “Those equations aren’t that different from what you learn in high school math,” she says.

Aurora studies all the ways these forces can affect her driving. Weeks before a race, she solves equations with a computer program. It figures out the fastest possible speed for her car on each turn. “Those equations aren’t that different from what you learn in high school math,” she says.

Later, during her practice laps on the track, sensors in her car record her velocity, or speed in a given direction, as well as the pressure applied to the brake pedal and how fast she switches back to the gas pedal. Comparing this real-world data with her computer calculations reveals where she can make time-shaving adjustments come race day.

“The difference between first place and third place is often tenths of a second or even less than that,” Aurora explains. “Studying data can be the difference between winning and losing a race.”

Later she takes practice laps on the track. Sensors in her car record her velocity, or speed in a given direction. They also record the pressure on the brake pedal and how fast she switches back to the gas pedal. She compares this real-world data with her computer results. That shows where she can make time-shaving changes on race day.

“The difference between first place and third place is often tenths of a second or even less than that,” Aurora explains. “Studying data can be the difference between winning and losing a race.”

Aurora employs another physics trick to help her win. As a race car speeds down the track, it experiences drag, or air resistance. “The force of the air hitting the front of your car pushes the car backward,” says Granade. As the air passes over the rear of the car, it forms swirling eddies that create more drag.

To reduce this resistance, Aurora often follows inches behind another car—a technique called drafting (see Getting a Boost). The car in front pushes air out of the way, says Aurora. “It creates a tunnel of sorts,” she says. With both vehicles so close together, air moves around them as if they’re a single car. That reduces drag on both cars so they can both move faster.

The two drivers cooperate only for a short time. “It’s a team sport until the last few laps,” says Aurora. “Then it’s just you and the car, and everyone else is your enemy.” The rear car might use the extra momentum it’s gained from drafting to zip around the lead car. From then on, it’s a battle to the finish.

Aurora uses another physics trick to help her win. When a race car speeds down the track, it runs into drag, or air resistance. “The force of the air hitting the front of your car pushes the car backward,” says Granade. When the air passes over the rear of the car, it forms rolling currents. This creates more drag.

To reduce drag, Aurora often uses a method called drafting (see Getting a Boost). She follows inches behind another car. The car in front pushes air out of the way, says Aurora. “It creates a tunnel of sorts,” she says. Both cars are so close together that air moves around them as if they’re one car. That reduces drag on both cars, so they can both move faster.

The two drivers work together only for a short time. “It’s a team sport until the last few laps,” says Aurora. “Then it’s just you and the car, and everyone else is your enemy.” The rear car has gained an extra push from drafting. It might use this to zip around the lead car. Then it’s a battle to the finish.

This fall, Aurora began her first semester at Harvard University in Massachusetts, where she plans to study mechanical engineering and literature. She wants to continue racing full-time for as long as she can, but she’s also considering a career in race car design. “Racing is 50 percent driving and 50 percent engineering,” she says.

Aurora hopes her success will encourage more women to get involved in the sport. “Role models are powerful,” she says. “If you see someone who looks like you doing something, it gives you more confidence that you can do it.”

This fall, Aurora began her first semester at Harvard University in Massachusetts. She plans to study mechanical engineering and literature. She wants to keep racing full-time for as long as she can. But she’s also thinking about becoming a race car designer. “Racing is 50 percent driving and 50 percent engineering,” she says.

Aurora hopes her success will lead more women to join the sport. “Role models are powerful,” she says. “If you see someone who looks like you doing something, it gives you more confidence that you can do it.”