1. Doppler Effect - By Jemma and Ruby
The Doppler effect causes the “neeeeeoowwm” sound of a speeding car passing by.

2. What is it?
When a sound source moves in relation to you, its pitch changes. From this effect you can determine whether the source is moving toward or away from you, and you can estimate how fast it’s going.
When a source moves towards an observer, the observed wavelength decreases and the frequency increases.
When a source moves away from an observer, the observed wavelength increases and the frequency decreases.

3. The Doppler Effect Experiment – The Doppler Ball.

4. What's going on?
When the distance between the source and receiver of waves remains constant, the frequency waves is the same in both places.
When the distance between the source and receiver of the waves is increasing, the frequency of the received wave forms is lower than the frequency of the source wave form.
When the distance is decreasing, the frequency of the received wave form will be higher than the source wave form.
Besides sound and radio waves, the Doppler effect also affects the light emitted by other bodies in space. If it is "red shifted" the light waves are spread apart, and it is traveling away from us. All other stars we have detected are "red shifted," which is one piece of evidence for the theory that the universe is constantly expanding, perhaps from a "big bang."