Consider a sound source producing sinusoidal waves moving towards an observer at a constant speed of $20 {ms}^{- 1}$ . If the observer is moving way from source at a constant speed of $10 {ms}^{- 1}$ , find the apparent wavelength of sound for the observer in metres. Frequency of source = $200 Hz$ and speed of sound in air is $340 {ms}^{- 1}$ . (Write upto two digits after the decimal point.)

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Solution

App. Wavelength $= λ = λ_{0} - V_{s} T = \frac{340}{200} - 20 [\frac{1}{200}] = 1.6 m$

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App. Wavelength =λ=λ0−VsT=340200−20[1200]=1.6 m

App. Wavelength $= λ = λ_{0} - V_{s} T = \frac{340}{200} - 20 [\frac{1}{200}] = 1.6 m$