## College Physics (4th Edition)

The correct answer is: (b) The car driver hears $440~Hz$, but the van driver hears a lower frequency.
The car driver is moving with the source so the car driver hears a frequency of $440~Hz$. The van driver is moving away from the source at a faster speed so the van driver hears a lower frequency. The correct answer is: (b) The car driver hears $440~Hz$, but the van driver hears a lower frequency.