Posted by Jake on .
Bat is flying 5m/s while chasing an insect that is flying in the same direction. The bat emits 40kHz chirp and hears a 40.4kHz reflected sound wave. What is the speed of the insect?
The reflected sound has a higher frequency, so the insect is approaching.
(delta f)/f = 0.4/40 = 0.01 = 2 V/a
The number 2 accounts for Doppler shift incident and reflected sound
a is the sound speed. Assume a = 340 m/s
V = 1.7 m/s