Question

When an automobile moves towards a listener, does the sound of its horn seem relatively low pitched, high pitched or normal?

Answer 1

Higher than normal pitch.

Explanation:

The peak of the sound wave that arrives at `t = t_1` did not have to travel as far as the previous peak did because the car came closer. That means that the time between the 2 peaks was less than if the car was standing still. Frequency, `f`, is

`f = "number of peaks"/(time)`

Therefore the frequency you heard was higher than if the car was standing still. Higher frequency means higher pitch.

I hope this helps,
Steve