Question

When a source moves away from a stationary observer, the frequency is 6/7 times the original frequency. Given: speed of sound = 330 m/s. The speed of the source is

• A. 40 m/s
• B. 55 m/s
• C. 330 m/s
• D. 165 m/s
  

Answer 1

The correct option is B 55 m/s

$v^{\prime }=\frac{v}{v+v_s}vor\frac{6}{7}v=\frac{330}{330+v_s}vor6\times 330+6v_s=7\times 330or6v_s=330or{v}_s=55m/s$