The Doppler Effect

A few weeks ago, I visited the Las Vegas Motor Speedway, a NASCAR racetrack. I got to watch cars speed around the track and I also rode in one. As the cars went around the track, the motors made a loud vroom noise and I noticed that the cars demonstrated the Doppler Effect. While watching from the pit, I could hear a change in pitch and volume while the car approached me and then sped passed me. They sounded like the motors made different noises as they drove by. However, when I was actually in the car, I realized that the motor made a constant vroom and sounded the same the entire time.

As the cars drive by, you can hear the sound of the motor change.

From inside the car, the engine makes a constant roar.