(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Assume: Take the speed of sound in air to be 341 m/s.

A bat, moving at 6.3 m/s, is chasing a flying insect.

The bat emits a 47 kHz chirp and receives back an echo at 47.73kHz.

At what speed is the bat gaining on its prey? Answer in units of m/s.

2. Relevant equations

f=initial frequency

fo=observed frequency

x= velocity of insect

f(observed)=f(init){(v+v[observer])/(v-v[source])}

3. The attempt at a solution

I determined the bat is the source, but because the chirp bounds off the insect and returns to the bat, I considered the insect to be the "source" in my equation:

Using the above equation:

f/fo=(343+Vbat)/(343+x)

46000/47730=(341+6.3)/(341+x)

.9637=347.3/(341+x)

341+x=346.3363

x=5.3363

then i take the velocity of the bat:

5.9-3.939=1.96

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# Homework Help: Doppler effect bat

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