Car "A" has a siren sounding a note of 540 Hz. A listener in car "B" hears a note of 544 Hz. Both move in the same direction. One concludes that:
Correct answer: D. "B" leads "A" and moves slower
- A. "B" leads "A" and move faster
- B. "B" is behind and moves slower
- C. Both move with same speed
- D. "B" leads "A" and moves slower
Explanation
As Car "A" is the source and car "B" observer.fB > fASo according to the Doppler effect, we can see that A is moving towards B, and as there is not much difference in their frequency and hence velocity this shows that "B" leads "A" and moves slower So, (D) is correct.
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Progressive waves transfer energy through oscillations, with wavelength, frequency, amplitude and wave speed related by v = fλ; sound speed depends on the medium. Superposition produces interference and stationary waves in strings and organ pipes, while simple harmonic motion describes the oscillation itself and must be distinguished from wave propagation.
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