Chapter 7.2

Question 1

Is sound a longitidunal or a transverse ewave

Answer 1

• it is a longitidunal wave
• > as such it can travel through solids, liquids and gases but cannot travel through a vacuum

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Question 2

How is sound produced

Answer 2

• it is produced by a mechanical disturbance of particles in a material along the sound wave’s direction of propagation
• > alternation between rarefaction and compression

Question 3

What is the source of any sound

Answer 3

• it is the ultimately the mechanical vibration of some frequency
• > this can be vibration of solids, liquids and or gases

Question 4

What is the definition of pitch

Answer 4

• it is the frequency of sound

- >lower frequency have lower pitch and higher frequency have higher pitch

Question 5

What is the Doppler effect

Answer 5

-it describes the difference between the actual frequency of sound and its perceived frequency when the source of the sound and sound’s detector are moving in relation to one another

• if source and detector are moving towards each other
• > then perceived frequency is greater than the actual frequency
• if source and detector are moving away from each other, then perceived frequency is less than actual frequency

-the sound waves behind the object are stretched out, while the sound waves in front of the object are being compressed

Question 6

What is the amplitude for sound waves related to

Answer 6

• it is related to the degree of compression of the medium

- >this creates a large pressure differential or pressure gradient

Question 7

What is a highly condensed wave front called

Answer 7

• it is called a shock wave
• > passing of a shock wave creates a very high pressure, followed by very low pressure
• > which creates a sonic boom

Question 8

What is the loudness or volume of sound

Answer 8

• it is the way in which we perceive sound intensity
• > perception of sound is subjective
• loudness depends on:
• > ear canal
• > stiffening of the ossicles
• > damage to cochlear hair cells by exposure to loud noises

Question 9

What is the definition of intensity

Answer 9

-it is the power transported per unit area

Question 10

How is intensity and amplitude related

Answer 10

-intensity is proportional to the square of the amplitude

Question 11

How is intensity related to the distance from the source that the sound is produced in

Answer 11

-intensity is inversely proportional to the square of the distance from the source

Question 12

Does damping have an effect on the frequency of a wave

Answer 12

• no it does not
• > therefore, the pitch will not change
• it does affect amplitude
• > so intensity and sound level(loudness) are also reduced

Question 13

What is beat frequency

Answer 13

• when two sounds of slightly different frequencies are produced in proximity
• > the differences between those two frequencies can be calculated

Question 14

Contrast a node from an antinode

Answer 14

Node
->no fluctuation in displacement of wave

Antinode
->points with maximum fluctuation

Question 15

Are strings closed at both ends?

Answer 15

• yes

- the harmonic is given by the number of half wavelengths supported by the pipe

Question 16

Are open pipes closed at both ends

Answer 16

• no
• > they are open at both ends(eg; a flute)

-note an open pipe has antinodes at both ends

Question 17

Describe the characteristics of a closed pipe

Answer 17

• one end is closed(node) and the other end is open(antinode)
• > odd number harmonics

-the harmonic is given by the number of quarter wavelengths supported by the pipe