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A SONAR system fixed in a submarine operates at a frequency 50 kHz. It is moving towards a rocky hill present inside water with a speed of 432 km h^(-1) . What is the apparent frequency of sound observed at the submarine after reflection by the rocky hill ? (Take velocity of sound in water to be 1450 m s^(-1) ) |
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Answer» Solution :(i) Doppler effect , `n^(1) = ((v)/(v - v_(s))) , n^(11) = n^(1) ((v+v_(0))/(v))` (ii) Consider the TWO cases . In the first case , consider the SUBMARINE as the source and rocky hill the observer of SOUND . Calculate the frequency as heard at the rocky hill USING the experssion for apparent frequency (Doppler's effect) . The frequency of sound reflected by the rocky hill is the same as that incident on it . In the SECOND case consider the rocky hill as the source and the submarine as the observer of sound . Now find the apparent frequency of sound as heard at the submarine using the experssion for apparent frequency . (iii) 59 Hz |
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