Chapter 16 review

    Conceptual questions
      Section 16.1
      1. A woman on a train hears a very loud siren from a long way away. She hears the frequency of the siren gradually decreasing but knows that the frequency of the siren should be constant. Which explanation is most likely correct?
        1. The train is moving toward the siren and slowing down.
        2. The train is moving toward the siren and speeding up.
        3. The train is moving at constant speed in a direction away from the siren.
        4. The train is moving at constant speed in a direction toward the siren.


      2. A guitarist presses his finger down in the middle of a string he is playing. How does this change the frequency of the sound produced by the string?

      3. Which equation best matches the meaning of this sentence?
        “The wavelength of a sound wave is the speed of sound divided by the frequency of the sound.”
        1. λ = v ÷ f
        2. λ = fv
        3. v = λf
        4. f = λ ÷ v


      4. Which has a higher frequency, a short-wavelength sound or a long-wavelength sound?

      5. Easy Do you think the equal-loudness curve is the same for bats and humans? Why?

      6. Easy Small animals typically have ears that are sensitive to higher frequencies than larger animals. Why might this be so?

      Section 16.2
      1. A microphone converts sound waves into electrical waves. What part of a stereo system converts electrical waves into sound waves?

      2. The identity of a single word is physically encoded in a sound wave as
        1. a different frequency.
        2. a pattern of different loudnesses.
        3. a pattern of changing amplitudes across many frequencies.
        4. a particular combination of certain frequencies heard together.


        Section 16.3
        1. Easy A student conducts an investigation into the resonance of sound by blowing air across the top of an empty soda bottle and measuring the frequency of the sound made by the bottle. The student then fills the bottle halfway with water. How should the frequency of the sound made by the half-full bottle compare to the frequency when the bottle was empty?

        2. Which is the best choice of materials to conduct an investigation into the resonance of sound?
          1. a ripple tank
          2. a plucked, taut string
          3. a pendulum
          4. a dropped wine glass


        3. Easy A student conducts the resonance and sound investigation on page 458.
          1. The student is unsure whether the resonance tube will resonate for any tube length when the tuning fork is held over it. Write a well-defined question for her to ask.
          2. Write down a testable hypothesis corresponding to this question.
          3. When she tests this hypothesis, what is the variable that she will change?
          4. Knowing what you do about resonance tubes, what will she observe?
          5. The student measured that the length of tube above the water line that resonated was 3 mm. Is this a reasonable measurement?
          6. The student wants to modify how she implements the investigative procedure by instead using a tube that is closed at the top. Is this an appropriate choice of equipment for studying resonance with this procedure?
          7. The student wants to see whether using a loud sound at the tube’s resonant frequency would cause the glass to break. (Do not try this yourself!) What would be an appropriate technology to choose to do this?

          4. Sabrina is listening to the sound produced by two speakers
        4. Easy Sabrina was investigating the sound produced by two small speakers connected to her laptop computer. She first placed the speakers side by side (“position A”) and listened to a tone at 400 Hz from several meters away, as illustrated in the drawing.
          1. As her lab partner Eko slowly moved one speaker closer to her, at “position B” Sabrina could barely hear the sound from the speakers. Why?
          2. Calculate the distance d between positions A and B. (The speed of sound is 343 m/s.)

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