Question

A whistle you use to call your hunting dog has a frequency of 21 kHz, but your dog is ignoring it. You suspect the whistle may not be working, but you can't hear sounds above 20 kHz. To test it, you ask a friend to blow the whistle, then you hop on your bicycle.

Answer 1

minimum speed to know if the whistle is working = 16.33m/s

Step-by-step explanation:

Speed of sound, v= 343m/s

Hearing frequency of dog, f= 21kHz

Hearing Frequency of man, fₐ= 20kHz

Minimum travel speed, vₐ=?

Using the formula;

fₐ=(1-vₐ/v)f

20=(1-vₐ/343)21

(1-vₐ/343)=20/21

vₐ/343=1-0.9524

vₐ=0.0476*343

vₐ=16.33m/s