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doppler effect?(20點)
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1.a truck moving at 25 m/s emits a 400-Hz signal.find the wavelength between the source and a stationary observer given that the truck is (A)approaching;(B)moving away.2.a source emit sound with a characteristic frequency of 200 Hz.calculate the observed frequency and the wave-length between source and observer in... 顯示更多 1.a truck moving at 25 m/s emits a 400-Hz signal.find the wavelength between the source and a stationary observer given that the truck is (A)approaching;(B)moving away. 2.a source emit sound with a characteristic frequency of 200 Hz.calculate the observed frequency and the wave-length between source and observer in each of the follow-ing situations:(A)the source approaches a stationary ob-server at 40 m/s 更新: 2.;(B)the observer approaches the stationary source at 40 m/s;(C)both the source and the observer move toward each other at 20 m/s relative to the ground.
(1) With reference to the equation of Doppler effect: 圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/April07/Doppler.jpg where f' = Apparent frequency f = Original source frequency v = Sound velocity uo = Observer's velocity us = Source's velocity Taking the sound velocity in air = 340 m/s, we have: Part (a) Apparent frequency f' = [(340 + 25)/(340)] × 400 = 429.1 Hz Therefore the apparent wavelength λ' = v/f' = 0.792 m Part (b) Apparent frequency f' = [(340 - 25)/(340)] × 400 = 370.6 Hz Therefore the apparent wavelength λ' = v/f' = 0.917 m (2) Again, applying the Doppler's effect equation again, we have: Part (a) Apparent frequency f' = [(340 + 40)/(340)] × 200 = 223.5 Hz Therefore the apparent wavelength λ' = v/f' = 1.521 m Part (b) Apparent frequency f' = [(340)/(340 - 40)] × 200 = 226.7 Hz Therefore the apparent wavelength λ' = v/f' = 1.5 m Part (c) Apparent frequency f' = [(340 + 20)/(340 - 20)] × 200 = 225 Hz Therefore the apparent wavelength λ' = v/f' = 1.511 m
其他解答:
doppler effect?(20點)
發問:
1.a truck moving at 25 m/s emits a 400-Hz signal.find the wavelength between the source and a stationary observer given that the truck is (A)approaching;(B)moving away.2.a source emit sound with a characteristic frequency of 200 Hz.calculate the observed frequency and the wave-length between source and observer in... 顯示更多 1.a truck moving at 25 m/s emits a 400-Hz signal.find the wavelength between the source and a stationary observer given that the truck is (A)approaching;(B)moving away. 2.a source emit sound with a characteristic frequency of 200 Hz.calculate the observed frequency and the wave-length between source and observer in each of the follow-ing situations:(A)the source approaches a stationary ob-server at 40 m/s 更新: 2.;(B)the observer approaches the stationary source at 40 m/s;(C)both the source and the observer move toward each other at 20 m/s relative to the ground.
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最佳解答:(1) With reference to the equation of Doppler effect: 圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/April07/Doppler.jpg where f' = Apparent frequency f = Original source frequency v = Sound velocity uo = Observer's velocity us = Source's velocity Taking the sound velocity in air = 340 m/s, we have: Part (a) Apparent frequency f' = [(340 + 25)/(340)] × 400 = 429.1 Hz Therefore the apparent wavelength λ' = v/f' = 0.792 m Part (b) Apparent frequency f' = [(340 - 25)/(340)] × 400 = 370.6 Hz Therefore the apparent wavelength λ' = v/f' = 0.917 m (2) Again, applying the Doppler's effect equation again, we have: Part (a) Apparent frequency f' = [(340 + 40)/(340)] × 200 = 223.5 Hz Therefore the apparent wavelength λ' = v/f' = 1.521 m Part (b) Apparent frequency f' = [(340)/(340 - 40)] × 200 = 226.7 Hz Therefore the apparent wavelength λ' = v/f' = 1.5 m Part (c) Apparent frequency f' = [(340 + 20)/(340 - 20)] × 200 = 225 Hz Therefore the apparent wavelength λ' = v/f' = 1.511 m
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