Answer:
Part A: What is the duck's speed? v=0.2m/s
Part B: How far apart are the crests behind the duck = 1m
Step-by-step explanation:
The concept applied here is the DOPPLER EFFECT, for example, if one is driving towards a station at 120km/hr, a higher frequency will be heard. and if you are driving away from the station at the same speed, one will hear a much more lower frequency. Tthese effect was proposed by the Austrian physicist by name Johann Christian doppler.
The detailed steps and appropriate formula is as shown in the attached file.