# Math Help - frequencies

1. ## frequencies

as a firetruck moves closer to you, you observe the frequency of the sirens to be higher. this is known as the doppler effect. in terms of the waves, why does this occur?

2. Originally Posted by johnnyc418
as a firetruck moves closer to you, you observe the frequency of the sirens to be higher. this is known as the doppler effect. in terms of the waves, why does this occur?
It is because the waves are approaching you as well as the firetruck. This means that waves emitted at the same frequency will be pushed closer together because the latter wave is emitted closer to you. This increased frequency is what the observer hears