College Park, MD (May 24, 2001)- The drivers competing in the Indianapolis 500 race this weekend will have to contend with more that just the other drivers-they'll have to battle the gravitational forces of physics.

In April, the Firestone Firehawk 600 Championship Auto Racing Teams (CART) race at Texas Motor Speedway was cancelled because most of the drivers became dizzy while practicing at speeds over 230 mph. Physicists say this is unlikely to happen during the Indianapolis 500 race. "Speed isn't the reason drivers get dizzy," says Dr. Richard Hewko, a professor of physics at East Kootenay Community College in British Columbia. "It's the speed and the driver's head position combined with the total forces acting on the driver."

These forces called G-forces (Gs) describe the amount of push or pull on an object, with 1 G equal to the gravitational force on an object at sea level. For example, 5Gs would equal 5 times the effect of gravity. G-forces can be front-to-back (Gx), side-to-side (Gy), and head-to-toe (Gz). When Gx forces increase, your body is pulled forward or pinned to the seat like an astronaut during liftoff. Gy forces push your body up against the side of the car like someone riding a rollercoaster, but when Gz forces increase on your body, it will feel heavier. "The blood that normally goes up to the arteries of the brain is pulled down by G-forces towards your feet," says Dr. Paul Werchan, a research physiologist at Brooks Air Force Base's Air Force Research Laboratory. "People can experience a wide variety of symptoms at 3Gs including dizziness and can loose consciousness at 5Gs." Werchan has been contacted by CART's medical team to help analyze the G-forces on the drivers practicing for the race in Texas.

To determine the total G-forces acting on a driver it is necessary to take into account the speed, and the position of the driver. Other crucial factors include the radius, length, and banking angle of the turns of the speedway. The Texas Motor Speedway's track has longer turns with higher banks at each corner than the Indianapolis 500 track. This affects the G-forces on the driver and how long they are acting on them. According to Beckman, at 230mph drivers at Texas Motor Speedway would feel G -forces of almost 5Gs for about 6 seconds, but in Indianapolis the drives would only feel G-forces of about 3Gs for about 4 seconds.

"Drivers feel the G-forces longer in the turns at Texas Motor Speedway than at the Indianapolis 500 track, " says Brian Beckman, physicist and member of the No Bucks Racing Club. "This might explain why the drivers had a harder time handling the turns even though their speeds were comparable to what they would drive at Indianapolis."

According to Hewko, the drivers head position also plays a role in how drivers handle turns. "The banking of the turns confuses the relationship between your eye, brain, and inner ear," says Hewko. "The inner ear tells the driver which way the G-forces are acting, but the force is not the typical down force of gravity-that's what makes drivers feel dizzy."

With the help of physics, drivers in this weekend's Indianapolis 500 race will be able to maintain their fast speeds without the threat of getting dizzy like the drivers at Texas Motor Speedway, but they still have to be driven to defy gravity.

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For more information:
Emilie Lorditch
(301) 209-3029

Indianapolis 500
Texas Motor Speedway
NASCAR
Championship Auto Racing Teams

Experts:
Dr. Richard Hewko
Physicist
East Kootenay Community College
250-489-2751 x424

Dr. Brian Beckman
Physicist
Member, No Bucks Racing Club
425-936-6314

Dr. Paul Werchan
Research Physiologist
Chief of Acceleration
Air Force Research Laboratory
Brooks Air Force Base
210-536-6325