9. Assume v is the speed of sound and f₀ is its frequency. If the sound source S moves toward an observer O at speed v_S and the observer O moves away from the sound source S at speed v_O. What is the frequency heard by O?
(A)
(B) 
(C)
(D) 
(E)
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統計: 尚無統計資料
統計: 尚無統計資料