Chapter 20: Problem 69

Question:        A person in a car blows a trumpet sounding at $\nu_0 = 438\ {\rm Hz}$. The car is moving toward a wall at $v=19.3\ {\rm m/s}$. Calculate

1.

The frequency of the sound received at the wall.

2.

The frequency of the reflected sound wave arriving back at the source.

Solution:        

$$\nu_{\rm wall} \nu_0\left({c\over c-v}\right)\ =\ 464.1\ {\rm Hz}$$ =

$$\nu_{\rm echo\ heard} \nu_0\left({c+v\over c-v}\right) )\ =\ 490.23\ {\rm Hz} \ \ \ .$$ = (13)