Question
Two trains A and B on platform are at a certain distance apart and sounding horn at same frequency. When a person standing between two trains starts running from train A towards B, he hears beats. Explain why.
Solution
When the person starts running from A to B, the frequency of the sound of the horn from train A received by the person will be more, and that of from train B will be less. The person hears the beats, due to the difference in the frequency of sound received.
