Fire up the wind tunnel and get ready to answer 30 questions about the many ways air flow affects the performance of cars on highways and speedways. Spoiler alert!
The term used to define and measure the air resistance acting against a moving car is…
coefficient of drag
lemniscate of Bernoulli
frictional eigenvalue
Correct Answer
Wrong Answer
Coefficient of drag is written as Cd in mathematical formulas.
Along with coefficient of drag, the most important aerodynamic aspect of a car's shape is…
frontal area
height
roof curvature
Correct Answer
Wrong Answer
A car with a low coefficient of drag can still have poor aerodynamics due to a large frontal area. For instance, a Sprint Cup car has a lower Cd than an F1 car because the F1's car's open wheels create a lot of drag, but the F1 car is more aerodynamic because of its tiny frontal area.
a flat panel that angles in toward the passenger compartment
a flat vertical panel
a gradual slope
Correct Answer
Wrong Answer
Any kind of abrupt change in body shape creates flow separation and low pressure/turbulence behind the car, so a gradual slope is best. Examples include the "fastback" window styles found in 60s and 70s muscle cars.
What helps create an area of high pressure over a car's trunk, negating the low pressure created by the rear window?
a wing
a spoiler
brake cooling vents
Correct Answer
Wrong Answer
A spoiler acts as an air dam, causing air to slow and compress above the trunk. Without it, flow separation would lead to an area of low pressure behind the rear window.
Does a wing on a race car act the same as a wing on an airplane?
Yes, but a wing on a car is inverted to provide downforce instead of lift.
No, it's a misconception that they perform similar functions because they were given similar names.
Yes, but other parts of the car's design must work to overcome the lift created by the wing.
Correct Answer
Wrong Answer
A wing on a car is an inverted airplane wing, curved to create low pressure on the underside of the wing and high pressure on top, which in turn creates downforce.
Which of these does NOT help create low air pressure underneath a car?
a raked angle, with the front of the car closer to the ground than the rear
ram air intake on the hood
side skirts
Correct Answer
Wrong Answer
Dropping the front of the car and adding side skirts keeps air pressure under the car low. A ram-air scoop can increase horsepower, but doesn’t affect underbody pressure.
seal off the area beneath the car, keeping all air flow out
expand the area under the car, accelerating the movement of air out from under the car, increasing downforce.
dissipate turbulence from the wheel wells
Correct Answer
Wrong Answer
A rear diffuser opens up the area under the car, allowing air to flow out from under the car more quickly and smoothly. This reduces the pressure and helps create downforce.
