A train blowing its whistle moves with constant
speed on a straight track towards observer and
then crosses him. If the ratio of difference between
the actual and apparent frequencies be 3:2 in the
two cases, then the speed of train is [v is speed of the sound]
1. 2v/3 2. v/5 3. v/3 4. 3v/2
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Answer:
Let velocity of train be v_{t} and velocity of sound be v.
1st case (when train is approaching observer) :
Now difference between apparent and actual frequency :
2nd case : (When train is going away from observer)
Now difference between apparent frequency and actual frequency :
Taking ratio as per question in both the cases :
So final answer :