# Person and a train

A train is moving on a straight track with speed $$20 \text{ ms}^{-1}$$. It is blowing its whistle at the frequency of $$1000 \text{ Hz}$$. What is the percentage change in the frequency heard by a person standing near the track as the train passes him?

Details and assumptions

• Speed of sound is $$320 \text{ ms}^{-1}$$
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