A SONAR system fixed on a submarine

Asked by pratikbharadia | 28th Nov, 2009, 01:57: PM

Expert Answer:

Dear student

Here there two things that are happening:

i. Source (submarine) stationary & the enemy ship (moving towrds Source) receiving the waves while in motion towrds the source.


The Doppler formula to be applied for Stationary source & observor moving towards the source is, so as to know the frequency received by the moving observer is:

here f' is the apparent frequency as heard by the moving enemy ship

f: frequency sent by source = 50 kHz

v is speed of sound waves in water =1500 m/s

v_o is the speed of enemy ship towards the source= 36 km/h = 10 m/s

substituting we obtain the frequnecy received by the moving enemy ship from the submarine is 50.333kHz.

2. Secondly, now the moving enemy ship reflects the thus received waves from the submarine back to the submarine...so this is case of moving source(enemy ship) & stationary observor (submarine).

the doppler formula to be applied is


here f' is apparent frequnecy as received by submarine

f  is the frequency reflected by enemy ship =50.33 kHz 

V is the speed of sound waves in water = 1500 m/s

Vs is the spped with which the enemy ship is moving towards the source= 10 m/s

substituing it in the above formula we get

f' = 50.66 kHz.






Answered by  | 30th Nov, 2009, 03:05: PM

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