SONAR and reflection head on

In summary: The frequency detected by sub A will be the same as the frequency of the original sonar wave, since the speed of the wave does not change. Therefore, the frequency detected by sub A will also be 1520 Hz.
  • #1
Two submarines are underwater and approaching each other head-on. Sub A has a speed of 12 m/s and sub B has a speed of 17 m/s. Sub A sends out a 1520 Hz sonar wave that travels at a speed of 1522 m/s.

... I already solved for this question ...

... What is the frequency of the sound detected by sub B (to the nearest Hz)? ...

... I used the Doppler equation and I got 1549 Hz as an answer, which is correct.

... My next question is ...

... Part of the sonar wave is reflected from B and returns to A. What frequency does A detect for this reflected wave (to the nearest Hz)?

... do I use the Doppler equation again ... or is there a reflection equation or concept that I missed out on?
 
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  • #2
sailordragonball said:
Two submarines are underwater and approaching each other head-on. Sub A has a speed of 12 m/s and sub B has a speed of 17 m/s. Sub A sends out a 1520 Hz sonar wave that travels at a speed of 1522 m/s.

... I already solved for this question ...

... What is the frequency of the sound detected by sub B (to the nearest Hz)? ...

... I used the Doppler equation and I got 1549 Hz as an answer, which is correct.

... My next question is ...

... Part of the sonar wave is reflected from B and returns to A. What frequency does A detect for this reflected wave (to the nearest Hz)?

... do I use the Doppler equation again ... or is there a reflection equation or concept that I missed out on?

Yes, you use it again, but perhaps not exactly the same way. Whatever the frequency of the reflected sound sub A is moving when it receives it.
 
  • #3


I can confirm that you are correct in using the Doppler equation to calculate the frequency detected by sub B. However, for the reflected wave, you will need to use the concept of reflection and the equation for calculating reflected frequency, which is given by f' = f(v + vr)/(v - vr), where f is the original frequency, v is the speed of sound in the medium, and vr is the relative velocity between the source and the reflecting object. In this case, the relative velocity would be the sum of the speeds of the two submarines, as they are moving towards each other. Therefore, the frequency detected by sub A for the reflected wave would be approximately 1544 Hz. I hope this helps.
 

What is SONAR and how does it work?

SONAR stands for Sound Navigation And Ranging. It is a technique used to detect and locate objects underwater by using sound waves. A SONAR system sends out a sound wave and measures the time it takes for the wave to reflect off an object and return to the system. By analyzing this data, the system can create a visual representation of the object's location and size.

What is the difference between active and passive SONAR?

Active SONAR is when the system emits its own sound wave and listens for the reflection. Passive SONAR, on the other hand, uses only the ambient sounds in the environment to detect objects. Active SONAR is more accurate but can be easily detected by other systems, while passive SONAR is harder to detect but less precise.

How is SONAR used in navigation and mapping?

SONAR is used in navigation and mapping by providing information about the depth and shape of the seabed. This information is used to create detailed maps of the ocean floor, which is crucial for safe navigation of ships and submarines. SONAR is also used to detect and map underwater obstacles or hazards that may be a danger to navigation.

What are some other applications of SONAR?

In addition to navigation and mapping, SONAR is also used in fish finding, underwater communication, and military applications such as detecting submarines. It is also used in scientific research to study marine creatures and their behavior, as well as in oil and gas exploration to locate potential drilling sites.

What are some limitations of SONAR technology?

SONAR can be affected by various factors such as temperature, salinity, and water currents, which can distort the sound waves and affect the accuracy of the data. It also has limited range and may not be able to detect objects that are too far away. Additionally, SONAR can be disrupted by other noise sources in the ocean, making it difficult to detect faint echoes from small objects.

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