Two cars travel in a straight line at the same speed; one car is ahead of the other. The car in the front blares its horn. The frequency as heard by the driver in the car behind
A) is higher.
B) is the same.
C) is lower.
D) cannot be determined.

Question

Quizplus · Accepted Answer

Since both cars are moving at the same speed in the same direction, there is no relative velocity between the source (the horn of the car in front) and the observer (the driver of the car behind). Therefore, according to the Doppler effect, the frequency heard by the driver in the car behind remains the same as the frequency of the source.

Two Cars Travel in a Straight Line at the Same