Question:
A stationary source emits sound waves of frequency 500 Hz. Two observers moving along a line passing through the source detect sound to be of frequencies 480 Hz and 530 Hz. Their respective speeds are, in ms-1, (Given speed of sound = 300 m/s)
A stationary source emits sound waves of frequency 500 Hz. Two observers moving along a line passing through the source detect sound to be of frequencies 480 Hz and 530 Hz. Their respective speeds are, in ms-1, (Given speed of sound = 300 m/s)
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For a stationary source and moving observer, \(f_{obs}=f\,\dfrac{v\pm v_o}{v}\); 480 Hz means the observer is receding and 530 Hz means approaching.
Updated On: Nov 5, 2026
- 12, 18
- 16, 14
- 12, 16
- 8, 18
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The Correct Option is A
Solution and Explanation
Observer 1 hears a lower frequency, so he moves away: \(480=500\,\dfrac{300-v_1}{300}\Rightarrow300-v_1=288\Rightarrow v_1=12\) m/s.
Observer 2 hears a higher frequency, so he moves toward the source: \(530=500\,\dfrac{300+v_2}{300}\Rightarrow300+v_2=318\Rightarrow v_2=18\) m/s.
Answer: (1) 12, 18
Observer 2 hears a higher frequency, so he moves toward the source: \(530=500\,\dfrac{300+v_2}{300}\Rightarrow300+v_2=318\Rightarrow v_2=18\) m/s.
Answer: (1) 12, 18
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