A sound source with a frequency of 1500 Hz moves at 40 m / s towards a reflecting wall approaching it at 50 m / s. If the speed of sound is 343 m / s determine the frequency that it detects the source of the reflected wave.

Given:

• The sound source moves with a frequency of f_o=1500 Hz
• The sound source moves with a velocity of v_s=40 m/s
• The reflecting wall approaching it at v_o= 50 m / s
• The speed of sound is v=343 m / s.

Determine the frequency that it detects the source of the reflected wave as follows using the Doppler effect.

$f=\left(\frac{1-{\displaystyle \frac{v_o}{v}}}{1-{\displaystyle \frac{v_S}{v}}}\right)f_o .......\left(1\right)$