When doing a sound experiment, you recorded the sound of a single frequency sound when it was stationary. You then placed the source on the back of your friend's bicycle and recorded the sound again as he rode away from you at 10 m/s. When the two recording are played simultaneously, you hear a beat frequency of 5.5 beats per second.
1. What was the frequency of the source?
2. What frequency did you hear as your friend rode away from you?