A dog whistle uses a frequency higher than humans can normally hear. A pet owner wants to test his dog whistle. The owner has a helper drive a car and blows the whistle while he stands on the sidewalk. In which direction should the driver drive so that the pet owner can hear it and why? * The driver should drive away from the pet owner to use the Doppler effect.
The driver should drive toward the pet owner to make the frequency lower.
The driver should drive away from the pet owner to change the speed of sound.
The driver should drive away from the pet owner to make the frequency higher.