A Source Moving Through Water at 10

Multiple Choice

A source moving through water at 10.0 m/s generates water waves with a frequency of 5.0 Hz. The speed of these water waves relative to the water surface is 20.0 m/s. The source approaches an observer who is at rest in the water. What wavelength would be measured for these waves by the stationary observer?

A) 1.0 m
B) 2.0 m
C) 4.0 m
D) 6.0 m
E) 8.0 m