[Home > Intro > The Doppler Effect]
To start, let's borrow an idea from the pages about sound: what a wave is. But instead of all of the fancy graphics, we'll draw the waves like this:
Here, the blue "waves" that go out are the pushes in the air that your ears respond to. The red dot at the center is a speaker pushing the air (producing the sound).
Ok? So to proceed with the Doppler Effect, look at the above animation and ask yourself:
This is a perfectly legitimate question. The red dot could be a police car moving with its siren on, or a person who is running while blowing a whistle.