Answer:
minimum speed to know if the whistle is working = 16.33m/s
Explanation:
Speed of sound, v= 343m/s
Hearing frequency of dog, f= 21kHz
Hearing Frequency of man, fâ= 20kHz
Minimum travel speed, vâ=?
Using the formula;
fâ=(1-vâ/v)f
20=(1-vâ/343)21
(1-vâ/343)=20/21
vâ/343=1-0.9524
vâ=0.0476*343
vâ=16.33m/s