A fire engine is moving at 40 m/s and sounding its horn. A car in front of the fire engine is moving at 30 m/s, and a van in front of the car is stationary

Question

Which observer hears the fire engine's horn at a higher pitch, the driver of the car or the driver of the van?

1. Both hear the same pitch.
2. The driver of the car hears the higher pitch.     
3. The driver of the van hears the higher pitch.

Answer 1

The van hears the higher pitch