How Does Dolphin Movement Affect Sound Frequency Perception?

[bfitzp]

Homework Statement

Dolphins emit clicks of sound for communication and echolocation. A marine biologist is monitoring a dolphin swimming in seawater where the speed of sound is 1523 m/s. When the dolphin is swimming directly away at 9.8 m/s, the marine biologist measures the number of clicks occurring per second to be at a frequency of 2230 Hz. What is the difference (in Hz) between this frequency and the number of clicks per second actually emitted by the dolphin?

Homework Equations

Fo = Fs(1/(1+v/Vs))

Fo = Frequency heard by observer
Fs = Frequency of source
v = speed of dolphn
Vs = speed of sound in water

The Attempt at a Solution

2230 = Fs(1/1+(9.8/1523))

2230 = (0.9936)Fs

Fs = 2244

Difference between Fs and Fo = 14 Hz. However the answer is showing as incorrect when I input it online. Any idea what I am doing wrong?

 

[cepheid]

Hi bfitzp

I actually used a sort of "common sense" approach to solving the problem (without resorting to that Doppler shift equation) and I got the same answer as you did. So I'm not sure what's wrong. The only thing I can think of is that the problem asks you for the difference between the observed and source frequencies, which would actually be -14 Hz (since the observed frequency < source frequency).

Either that, or your computer wants more sig. figs.?