- Learn about downforce
- Demonstrate how air pressure works in an experiment
- Pressure-Test Spool Assembly Sheet
- Under Pressure Activity Sheet
- Race Car Adaptations Resource Sheet
- A Focus on Air Pressure Resource Sheet (optional)
- Recycled or reused paper (1 sheet per student)
- Straws (1 per student)
- Spools (1 per student)
- Index cards (1 per student)
- Card stock (1 sheet per student)
- Completed cars
Note: Students will need one whole straw, plus the piece of straw left over from Lesson 1. Students will reuse the card stock from Lesson 1.
Make copies of each activity and resource sheet for each student in your class.
Think: How are aerodynamics of racing and flight similar?
- Explain that because NASCAR race cars can reach speeds of more than 200 miles per hour, they rely on air pressure and special race car adaptations to stick to the track. Air pressure—a key element of aerodynamics—is a force caused by the weight of air molecules pushing against an object’s surface.
- Fast-moving air causes low air pressure, and slow-moving air creates high air pressure. Downforce is created when high pressure pushes down on an object from above and there is low pressure below. Lift—the opposite of downforce—is created when there is low pressure above an object and high pressure below.
Move: How does air pressure cause an object to rise or fall?
Step 1: To demonstrate how air pressure works, have each student hold the short end of a sheet of paper with his or her hands pointing up. The paper should curve down over the back of his or her hands. Tell the students to blow forcefully over the curve of the paper. What happens? (Faster-moving air over the top of the paper creates lower pressure above in contrast to higher pressure below. That creates lift, causing the paper to rise.)
Step 2: Next have students fold 1-inch flaps along the two shorter edges of the paper. Have them turn the paper over and fold two more 1-inch flaps along those same edges. Finally, have them set the paper on a tabletop so that there is a gap between the paper and the table. Ask them to blow forcefully through the gap. What happens? (Faster-moving air below the paper creates an area of low pressure. The high pressure above pushes downward, creating downforce and causing the paper to sag.)
Build: What is the relationship between air speed and air pressure?
Step 1: Pass out the Pressure-Test Spool Assembly Sheet, the Under Pressure Activity Sheet, and experiment materials. Have pit crews complete the experiment. If students have trouble, make sure the straws are not taped at an angle and the top of the spool is completely covered.
Step 2: After groups complete the Conclusions questions, challenge them to think of other objects that rely on lift or downforce to operate. (Answer Key: Experiment: fast/low; slow/high; low/fast; high/slow; low/ high/lift. Race car: slow/high; fast/ low; high/slow; low/fast; high/low/ downforce.)
Team Up: How do race car modifications influence downforce on the vehicle?
Step 1: Pass out copies of the Race Car Adaptations Resource Sheet. Point out the race car’s splitter and skirting. Explain that these adaptations enhance the car’s downforce by directing fast-moving air underneath it (splitter) and preventing slow-moving air from slipping underneath its sides (skirting).
Step 2: Pass out card stock, scissors, and the completed cars from Lesson 1. Have pit crews use Race Car Adaptations Resource Sheet to guide them in adding spoilers, splitters, and other features to their cars. After they have adapted their race cars, ask students to write two or three paragraphs explaining:
- How the speed of air flow creates air pressure, drag, and downforce
- How a race car’s spoiler increases drag and creates downforce
- How a race car’s splitter and skirting help keep the car on the track
You may choose to share A Focus on Air Pressure Resource Sheet with students for a visual illustration of where race cars experience air pressure.