Chapter 26

Question 1

Where do all sounds originate from?

Answer 1

In the vibrations of material objects

Question 2

List the process of making sounds

Answer 2

1). The orginial vibration stimulates the vibration of something larger or more massive
2). This vibrating material then sends a disturbance through a surrounding medium, usually air, in the form of longituduinal waves

Question 3

Under ordinary conditions, the frequency of the sound waves produced ___________the frequency of the vibrating source

Answer 3

equals

Question 4

Pitch

Answer 4

The word used to describe our sujective impression about the frequency of sound

Question 5

A high-pitched sound has a ____________frequency

Answer 5

high vibration

Question 6

A low-pitched sound has a ____________frequency

Answer 6

low vibration frequency

Question 7

Sound waves with frequencies below 20 Hz are

Answer 7

Infrasonic

Question 8

Sound waves with frequencies above 20,000 Hz are

Answer 8

Ultrasonic

Question 9

Can humans hear infrasonic and/or ultrasonic waves?

Answer 9

No

Question 10

When you open a door quickly…

Answer 10

The door pushes molecules from their original positions, into their neighbors, and so on, like a compression wave, until a curtain flaps out the window. A pulse of compressed air has moved from the door to the curtain.

Question 11

Compression

Answer 11

A pulse of compressed air

Question 12

When you quickly close the door, the door pushes neighboring air molecules out of the room, what happens?

Answer 12

This produces an area of low pressure next to the door, neighboring molecules then move into it, leaving a zone of lower pressure behind them. Other molecules farther from the door move into these rarefied regions, resulting in a pulse of rarefied air moving from the door to the curtain.

Question 13

Rarefied

Answer 13

The air in the zone of low pressure

Question 14

Rarefaction

Answer 14

The pulse of low-pressure air

Question 15

For all wave motion, it is not the medium that travels actoss the room, but…

Answer 15

a pulse that travels

Question 16

As a source of sound _________, a series of ___________and ______________travels outward from the source

Answer 16

vibrates; compressions; rarefactions

Question 17

Most sounds you hear are transmitted through…

Answer 17

the air

Question 18

Sound travels in…

Answer 18

solids, liquids, and gases

Question 19

What types of matter are generally good conductors?

Answer 19

gases and liquids

Question 20

The speed of sound differs in different materials. T or F

Answer 20

T

Question 21

Sound is transmitted faster in ______, than in ________, and still faster in _______.

Answer 21

liquids; gases; solids

Question 22

The transmission of sound requires a…

Answer 22

medium

Question 23

If there is nothing to compress and expand…

Answer 23

there can be no sound

Question 24

Which is faster sound or light?

Answer 24

light

Question 25

The speed of sound in a _____depends on the ___________of the _________and the _______of the particles in the gas

Answer 25

gas; temperature; gas; mass

Question 26

For each degree increase in air temp. above 0 degrees Celsius, the speed of sound in air increases by about...

Answer 26

0.60 m/s

Question 27

At a normal room temp of 20 C, sound travels...

Answer 27

about 340 m/s

Question 28

The speed of sou nd in a solid amterial depends not on the material's density but its..

Answer 28

elasticity

Question 29

Elasticity

Answer 29

The ability of a material to change shape in response to an applied force, and then resume its initial shape once the distroting force is removed

Question 30

THe speed of sound depends on an object's...

Answer 30

Elasticity

Question 31

The intensity of a sound is proportional to the...

Answer 31

square of the amplitude of a sound wave

Question 32

Sound intensity is _______and is measured by _________.

Answer 32

objective; instruments

Question 33

Loudness is a ________sensation sensed in the brain.

Answer 33

physiological

Question 34

What is the unit of intensity.

Answer 34

decibel

Question 35

An increase of each 10dB means that sound intensity increases by a factor of 10. T or F

Answer 35

T

Question 36

Physiological hearing damage begins at exposure to ...

Answer 36

85 dB

Question 37

When any object composed of an _______material is _________, it vibrates at its own special set of frequencies, which together form its special sound.

Answer 37

elastic; disturbed

Question 38

natural frequency

Answer 38

the frequency at which an object vibrates when it is disturbed

Question 39

What does natural frequency depend on?

Answer 39

The elasticity of the object

Question 40

A natrual frequency is one at which______________ is required to produce ___________.

Answer 40

minimum energy; vibrations

Question 41

Forced vibration

Answer 41

when an object is made to vibrate by another vibrating object that is nearby

Question 42

Resonance

Answer 42

a phenomenon that occurs when the frequency of a vibration force on an onject matched the object's natural frequency and a dramatic increase in amplitude occurs. To re-sound

Question 43

An object resonates when there is a _______to pull it back to its starting position and enough ______ to keep it vibrating

Answer 43

force; energy

Question 44

Resonance occurs when...

Answer 44

successive impulses are applied to a vibrating object in rhythm with its natural frequency

Question 45

Can sound waves interfere?

Answer 45

Yes

Question 46

For sound, the crests of the wave = ____________, and the trough of the wave = ___________.

Answer 46

compression; rarefaction

Question 47

In either case, in a sound wave, there is a _____________and ___________.

Answer 47

constructive interference and an increase in amplitude.

Question 48

Why is destructive interference usually never a problem?

Answer 48

Bc there is usually enough reflection of sound to fill in canceled spots.

Question 49

When two tones of slightly different frequency are sounded together...

Answer 49

a regular fluctuation in the loudness of the combined sounds is heard

Question 50

Beats

Answer 50

periodic variation in the loudness of sound

Question 51

When can beats be heard?

Answer 51

When two slightly mismatched tuning forks are sounded together

Question 52

In general, when two people with different strides walk together...

Answer 52

the number of times they are in step in each unit of time is equal to the difference in the frequencies of their steps.

Question 53

When does minimum and maximum amplitude occur?

Answer 53

when both waves are in phase and out phase

Question 54

Can beats occur with any kind of wave?

Answer 54

Yes

Question 55

When the frequencies are identical, what happens to the beats?

Answer 55

They disappear