Sections 2 & 3: Here's the definition of the doppler effect, if you didn't have the chance to write it down in class today:
The Doppler Effect is a result of the compression and expansion of waves due to the motion of the source or the detector.
Now answer the following questions in your notebook:
1) At a swimming pool, a music fan up on a diving platform is listening to a radio. As the radio is playing a tone that has a constant frequency, fs, it is accidentally knocked off the platform. Describe the Doppler effect heard by (a) the person on the platform and (b) a person down in the water. In each case, state whether the observed frequency, f0, is greater than fs and describe how f0 changes (if it changes) as the radio falls (you may want to draw a picture).
2) You are heading toward an island in a speedboat and you see your friend standing on the shore, at the base of a cliff. You sound the boat’s horn to alert your friend of your arrival. If the horn has a rest frequency of f0, does your friend hear a higher, lower or equal frequency? Explain.
3) A fire engine is moving at 40 m/s and sounding its horns. A car in front of the fire engine is moving at 30 m/s, and a van in front of the car is stationary. Which observer hears the fire engine's horn at higher pitch, the driver of the car or the van?
4) A bat flying toward a wall emits a chirp at 40 kHz. Is the frequency of the echo received by the bat greater than, less than, or equal to 40 kHz? Explain.
