Physics-
General
Easy
Question
A source of sound is travelling at 
along a road, towards a point A. When the source is 3m away from A, a person standing at a point O on a road perpendicular to the track hears a sound of frequency ‘n ’. The distance of O from A at that time is 4m. If the original frequency is 640 Hz, then the value of n is (given velocity of 
- 620 Hz
- 680 Hz
- 720 Hz
- 840 Hz
The correct answer is: 840 Hz
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