Unit 4 Review

1. A few boys are sledding on snow in their favorite park. They notice that it is harder to hear someone shouting from the top of the hill to the bottom than it is in the summer. What factor is most likely affecting the sound of their shouting?

• A. altitude
• B. frequency
• C. pressure
• D. temperature

2. The diagram below shows a sound wave traveling through air. Which terms best describes points N and M as the wave progresses?

• A. crests
• B. troughs
• C. rarefactions
• D. compressions

3. Which of the following is the best example of resonance?

• A. a bat uses ultrasonic waves to lovate its next meal
• B. a telephone changes sound waves into electric signals
• C. a guitar body vibrates from the sound of a plucked string
• D. a jet produces a sonic boom as it breaks the sound barrier

4. Which of the following accurately describes a difference between an audio CD and a digital file?

• A. Sounds can be stored on an audio CD but not in a digital file.
• B. Unlike a digital file, an audio CD does not require a computer to record and play back sound.
• C. An audio CD stores sounds as grooves on the CD's surface, whereas a digital file stores sounds as computer code.
• D. Unlike the information stored on an audio CD, the information stored ina digital file can be converted into sound waves.

5. Two police cars are driving down the highway at 80 km/h. The first car turns on its siren, which has a frequency of 650 Hz. What frequency will the police officer in the second car hear?

• A. 650 Hz
• B. less than 650 Hz
• C. greater than 650 Hz
• D. There is not enough information to answer the question.

6. For what purpose do bats use ultrasonic waves?

• A. sonar
• B. ultrasound
• C. echolocation
• D. Doppler effects

7. A sound wave travels through air at a speed of 350 m/s. Which of the following most likely describes the speed of that sound wave through water?

• A. 350 m/s
• B. less than 350 m/s
• C. greater than 350 m/s
• D. There is not enough information to answer this question.

8. A game show is creating soundproof booths for contestants. Which material should be used on the walls inside the booth?

• A. wood panels
• B. wedged foam
• C. stainless steel plates
• D. concrete

9. Which of the following shows the destructive interference of two transverse waves?

• A.
• B.
• C.
• D.

10. What role does the outer ear play in hearing?

• A. captures sound waves
• B. transmits sound waves into electrical signals
• C. converts sound waves into electrical signals
• D. removes high and low sound waves that are harmful