ASSIGNMENT 4 Textbook Assignment: “Antisubmarine Warfare,” chapter 4, pages 4-1 through 4-17. 4-1. Sonar is an acronym derived from using the first letters of what terms? 1. Sound, Navy, return 2. Sound, naval, rate 3. Sound, navigation, ranging 4. Sound, NAVAIR, range 4-2. Echo-ranging sonar relies on the reception of an echo to determine what information about a target? 1. Range only 2. Bearing only 3. Range and bearing only 4. Range, bearing, and frequency 4-3. What type of sonar does NOT transmit sound, but functions by receiving sound from the target? 1. Active 2. Passive 3. Reverberation 4. Return 4-4. A high-pressure area occurs in the water next to a hydrophone each time the hydrophone moves in what direction? 1. Inward only 2. Outward only 3. Upward only 4. Downward only 4-5. The high-pressure area in a sound 4-6. wave is known as 1. depression 2. rarefaction 3. compression 4. wavelength The low-pressure wave is known as a area in a sound a 4-7. 4-8. 4-9. 4-10. 4-11. The wavelength of a sound wave is equal to the distance between two successive 1. rarefactions only 2. compressions only 3. rarefactions or compressions 4. diaphragm vibrations The frequency of a sound wave is defined as the number of which of the following item 1 second? 1. Wavelengths 2. Compressions 3. Rarefactions 4. Depressions that occurs in Absorption of sound waves in the ocean is least during which of the following water conditions? 1. White-capped waves 2. Smooth sea surface 3. Ship’s wake 4. Riptides Absorption of sound waves in the ocean is greatest during which of the following transmissions? 1. Low frequency 2. High frequency 3. Low amplitude 4. High amplitude Foreign matter in seawater includes which of the following items? 1. Silt and animal life only 2. Animal life and seaweed only 3. Silt and seaweed only 4. Silt, animal life, seaweed, and air bubbles 1. depression 2. rarefaction 3. compression 4. wavelength 23