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A submarine (A) travelling at 18 km/hr is being chased along the line of its velocity by another submarine (B) travelling at 27 km/hr. B sends a sonar signal of 500 Hz to detect A and receives a reflected sound of frequency ν . The value of ν is close to: (Speed of sound in water =1500 ms –1 )

1. 507 Hz
2. 504 Hz
3. 499 Hz
4. 502 Hz

Correct answer: 502 Hz

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