14: Sound

Question 1

Define sound.

Answer 1

Sound is a form of energy that is transferred from one point to another as a longditudinal wave.

Question 2

How is sound produced?

Answer 2

Sound waves are produced by vibrating sources placed in a medium, which can be a solid, liquid, or gas.

Question 3

Describe how energy is transferred in a medium.

Answer 3

The source (tuning fork) oscillates (vibrates) in the medium and transfers its kinetic energy to the particles near it. The particles then vibrate and transfer kinetic energy to the particles further away, transferring the energy without transferring the medium.

Question 4

What are pitch and volume related to?

Answer 4

Pitch : frequency (larger λ = higher pitch)
Volume : amplitude (larger A = higher volume)

Question 5

What are the two graphs relating to sound waves?

Answer 5

Displacement-distance and pressure-distance graphs.

Question 6

How does the speed of sound differ in different mediums? Explain why.

Answer 6

Sound travels fastest in solids, followed by liquids, then gases. (in air, 330 m/s)

The particles in solids are far closer together than in gases, meaning the transfer of energy through vibrations occurs much faster.

Question 7

What is the formula for calculating speed of sound?

Answer 7

v = d/t
(m s ^-1)

Question 8

Define echo.

Answer 8

The repetition of sound due to the reflection of sound. Echoes obey all laws of reflection.

Question 9

State three applications of echoes.

Answer 9

• Measuring large distances
• Detecting the locations of objects (echolocation)
• Sonar (sound navigation and ranging) for sea navigation