Question 1

Which of the following best describes the nature of sound waves in air?

Accepted Answer

Sound waves are longitudinal waves consisting of alternating regions of high and low pressure.

Question 2

A person hears thunder 3 seconds after seeing a lightning flash. Assuming the speed of sound is $$330\ \mathrm{m/s}$$, how far away is the lightning?

Accepted Answer

$$990\ \mathrm{m}$$

Question 3

Which of the following statements about the speed of sound is correct?

Accepted Answer

Sound travels faster in denser and more rigid materials because molecules are closer together.

Question 4

If the frequency of a sound wave increases while its speed remains constant, what happens to its wavelength?

Accepted Answer

The wavelength decreases.

Question 5

A tuning fork vibrates at $$256\ \mathrm{Hz}$$ and produces a sound wave in air where the speed of sound is $$340\ \mathrm{m/s}. $$What is the wavelength of the sound produced?

Accepted Answer

$$1.33\ \mathrm{m}$$

Question 6

Which of the following best explains why you can hear a train coming by placing your ear on the rail before you hear it through the air?

Accepted Answer

Sound travels faster in the rail because it is a more rigid and elastic medium.

Question 7

Which of the following is an example of resonance?

Accepted Answer

A child pumping a swing at the same rhythm as the swing's natural frequency, causing the amplitude to increase.

Question 8

A musician hears 5 beats per second when playing a note along with a reference tone of $$440\ \mathrm{Hz}. $$What are the possible frequencies of the note being played?

Accepted Answer

$$445\ \mathrm{Hz}$$\ or\ $$435\ \mathrm{Hz}$$

Question 9

Which of the following best describes constructive interference of sound waves?

Accepted Answer

Two sound waves meet in phase and their amplitudes add, resulting in a louder sound.

Question 10

Noise-cancelling headphones use which principle to reduce unwanted ambient sound?

Accepted Answer

Destructive interference

Question 11

On a cold night, sound travels across a lake more easily than during the day. This is primarily because:

Accepted Answer

Sound waves are refracted downward due to cooler air near the ground.

Question 12

Which of the following is NOT a property of sound waves?

Accepted Answer

They can travel through vacuum.

Question 13

A sound wave has a frequency of $$500\ \mathrm{Hz}$$ and a wavelength of $$0.68\ \mathrm{m}. $$What is the speed of sound in this medium?

Accepted Answer

$$340\ \mathrm{m/s}$$

Question 14

Which of the following best explains why older adults often struggle to hear very high-pitched sounds?

Accepted Answer

The range of frequencies detectable by the human ear narrows with age, especially at the high end.

Question 15

Which of the following is a practical application of ultrasonic waves?

Accepted Answer

Medical imaging such as ultrasound scans

Question 16

If you shout near a large, hard wall, you hear an echo. This is due to:

Accepted Answer

Reflection of sound

Question 17

Which of the following best describes beats?

Accepted Answer

Periodic variations in loudness due to interference of two waves with slightly different frequencies

Question 18

A concert hall designer wants to maximize reverberation. Which material should be used for the walls?

Accepted Answer

Hard, rigid surfaces

Question 19

Which of the following is true about the relationship between frequency ($$f$$), wavelength ($$\lambda$$), and speed ($$v) of a $$sound wave?

Accepted Answer

$$v = f \lambda$$

Question 20

Which of the following animals uses infrasonic frequencies to communicate?

Accepted Answer

Elephants

Chapter 20: Sound – Nature, Properties, and Phenomena

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