The science behind the extremely fast cars

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THE PHYSICS OF NASCAR

By Diandra Leslie-Pelecky

Dutton, $25.95, 286 pages

REVIEWED BY JOANNE MCNEIL

Even diehard NASCAR fans might believe racing cars is not much different from driving a normal car extremely fast, but Diandra Leslie-Pelecky, University of Texas-Dallas physics professor and author of "The Physics of NASCAR" explains there is a lot more to it than that.

Her book explains the sport works at the "limits of what we understand about aerodynamics, structural engineering, and even human physiology … Crew members — even if they can't recite Newton's Laws of Motion — have used these principles since the sport began to makecars faster and safer. Although they might not use the same words I use, NASCAR drivers quickly develop an intuitive understanding of the principles of aerodynamics and kinematics—or they crash a lot." This behind-the-scenes look at the science of the sport is an exciting lesson for those of us who might not have considered Newton's laws since high school.

A NASCAR race car enters turn three at the Las Vegas Motor Speedway at 170 mph. That sounds extremely fast already, but it is even more impressive when you consider, as Ms. Leslie-Pelecky explains, a Boeing 757 touches down a runway at roughly the same speed. And a Boeing isn't positioned, like a race car, just inches away from another vehicle while it travels at such a high speed. How are these vehicles designed to protect the driver and maintain shape in such high speeds?

Ms. Leslie-Pelecky starts explaining the skeleton structure of the vehicle — the chassis — works like the bones in your body. Drivers modify their vehicles depending on weather and tracks, "sheet metal gets put on and cut off, and engines, springs, and shocks are installed and removed but the chassis really is the car."

National Association for Stock Car Auto Racing mandates certain sizes for parts and wall thickness for the same reasons the Boyscout Pinewood derby require cars under a certain weight — drivers need to start with a roughly even base. After that, it is up to the mechanics.

Teams customize the bodies of their cars not just to the type of tracks, but every individual track. Small changes in the shape of the vehicle can produce the difference between winning and losing a race. Even still, an unexpected change in the weather might turn a brilliantly crafted car into a "slug." Good mechanics are extremely intuitive about the racetrack working conditions.