A person moves with a speed 1/3 the speed of sound waves towards the stationary source of sound. Then the frequency of sound waves heard by the person will:
Correct answer: C. 4/3 f
- A. 2/3 f
- B. 3/2 f
- C. 4/3 f
- D. 3/4 f
Explanation
For observer moving towards stationary source: f' = f(1 + vobs /v). With vobs = (1/3)v, f' = f(1 + 1/3) = (4/3) f. So observed frequency increases to 4/3 times f.
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About Waves
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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