The apparent frequency of the whistle of an engine changes in the ratio 6:5 as engine passes a stationary observer. If the speed of sound is 352 m/s. Then the speed of engine will be:
Correct answer: B. 32 m/s
- A. 22 m/s
- B. 32 m/s
- C. 27 m/s
- D. 36 m/s
Explanation
The apparent frequency of the whistle of an engine changes in the ratio 6:5.The Doppler effect is given by the following formula: f' = f * (v + u)/(v - u).The speed of the sound is 352 m/s.The apparent frequency is 6f/5.Solving for the speed of the source (u), we get u = 32 m/s.
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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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