Sound and Wave - Doppler Effect

A source of 1-kilohertz sound is moving straight toward you at a speed 0.9 times the speed of sound. The frequency you receive is 

A. 0.1 kHz
B. 0.5 kHz
C. 1.1 kHz
D. 1.9 kHz
E. 10 kHz

(GR8677 #12)

Solution:

Moving toward observer
→ f increases
→ f  > 1 kHz
→ A and B are FALSE

Speed 0.9 times the speed of sound
→ f increases greatly
→ E. TRUE

Answer: E

Calculation:





+ sign = receding
− sign = approaching