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A motor cyclist moving with 30 km/ h blows a whistle of 476 Hz towards a cliff. If velocity of sound is 1220 Km/h, the apparent frequency of the echo heard by him is : |
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Answer» 250 Hz `v. = ((1220)/(1220 - 30)) 476 = 488 Hz.` ` therefore` FREQUENCY of reflected wave i.e., ECHO is 488 Hz and observer is moving towards it. `therefore v.. = ((1220 + 30)/(1220)) 488`= 500 Hz. hence the correct choice is (b) . |
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