A train standing a the outer signal of a railway station blows a whistle of frequency 400Hz in still air . when the train
(i) approaches the platform with a speed of `10ms^(-1)` ?
(ii) recedes from the platform with a speed of `10 ms^(-1)` ?
What is the speed of sound in each case ? The speed of sound in still air can be taken as `340ms^(-1)`

Explanation

Relative velocity of sound with respect to the source in the first case will be `330 ms^(-1)` and in the latter `350 ms^(-1)` . The relative velocity of sound with respect to the observer will be `340 ms^(-1)`