as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
give three examples of the doppler effect.
user
three examples of the doppler effect are:
1. the sound of a police siren changing pitch as it passes by.
2. the red shift seen in the spectrum of distant galaxies due to the universe expanding. 
3. the change of pitch heard in a lightning strike as the lightning moves away from the observer.
assistant