Review Questions for sound

Question 1How does sound travel from its

source to your ear?

a. By changes in air pressureb. By vibrations in wires or stringsc. By electromagnetic wavesd. By infrared waves

Question 2Paulo is listening to classical music in the

speakers installed in his swimming pool. A note with a frequency of 327 reaches his ears while he is underwater. What is the wavelength of

the sound that reaches Paulo’s ears? Use 1493 m/s for the speed of sound in water.

1. 2.19x10-8 m2. 0.219 m3. 4.88x10-5 m4. 4.57 m

Question 3

The sound of a trumpet travels in 33.3°C air. If the frequency of the

note is 298 Hz, what is the wavelength of the note?

1. 9.93x10-4 m2. 0.849 m3. 1.18 m4. 1.05x105m

Question 4The horn of a car attracts the attention of a stationary observer. If the car is

approaching the observer at 60.0 km/h, what is the frequency of the sound perceived by the observer?

1. 488 Hz2. 512 Hz3. 538 Hz4. 600 Hz

Question 5A car is receding at 72 km/h from a

stationary siren. If the siren is wailing at 657 Hz, what is the frequency of the

sound perceived by the driver?

1. 543 Hz2. 620 Hz3. 647 Hz4. 698 Hz

Question 6Which of the following pairs of instruments have

resonant frequencies at each whole number multiple (2,3,4…) of the lowest frequency?

1. A clamped string and a closed pipe2. A clamped string and a open pipe3. An open pipe and a closed pipe4. An open pipe and a reed instrument

Question 7

• What physical values do you use to describe sound waves?

Question 8

• When timing the 100 meter run, officials at the finish line are instructed to start their watches at the sight of the smoke from the starter’s pistol and not at the sound of its firing. Explain. What would happen to the times for the runners if the timing started when the sound was heard?

Question 9

• Does the Doppler shift occur for only some types of waves? Explain your answer

Question 10

• How can a certain note sung by an opera singer cause a crystal glass to shatter?

Question 11

• What is necessary for the production and transmission of sound?

Question 12

• In the military, as marching soldiers approach a bridge, the command “route step” is given. The soldiers then walk out of step with each other as they cross a bridge. Explain.

Question 13

• Why don’t musical instruments sound like tuning forks?

Question 14

• Explain how the slide of a trombone changes the pitch of the sound in terms of being a resonance tube.

Question 15

• In a science fiction movie a satellite blows up. The crew of a nearby ship immediately hears and sees the explosion. If you were hired as an advisor, what physics errors would you identify?

Question 16

• Give an estimate of the distance to a lightning strike from you if it took the resulting thunder 2.5 seconds to reach your ear

Question 17

• Does the sound of 40 dB have a factor of a 100 times greater pressure variation than the threshold of hearing, of a factor of 40 times greater? Explain.

Question 18

• The sound by bats has a wavelength of 3.5 mm. What is the sound’s frequency in the air?

Question 19

• A rock band plays at an 80 dB sound level. How many times greater is the sound pressure from another band playing at each of the following sound levels:

• 100 dB• 120 dB