試題詳解

23. A girl is sitting near the open window of a train that is moving at a velocity 10.00m/s to the east. The girl’s uncle stands near the tracks and watches the train move away. The locomotive whistle emits sound at the frequency of 500.0 Hz. The air is still. What frequency does the uncle hear? (The speed of sound is 343m/s.)
(A) 471.7 Hz
(B) 485.8 Hz
(C) 500.0 Hz
(D) 515.0 Hz
(E) 530.0 Hz