Wave Speed and Sound

Question 1

the _________ of a wave is
the number of complete cycles that pass
a given point in the medium per a unit of
time.

Answer 1

frequency

Question 2

The frequency of the wave is the same
as the frequency of the ______. It is the
_______ alone that determines the
frequency of the wave.

Answer 2

source; source

Question 3

Once the wave is
produced, the frequency ______ changes,
even if its speed and wavelength do.

Answer 3

never

Question 4

Likewise the _____ of the wave can
never change, because it is the _____
of the frequency.

Answer 4

period; inverse

Question 5

________ is defined as the time it takes to
go a certain distance.

Answer 5

Speed

Question 6

For a wave, we consider the speed of
the wave to be the distance traveled by
the wave during one ______ or ______ of
the source.

Answer 6

cycle; period

Question 7

Waves travel ____ wavelength in the time
required for one complete vibration of the
source.

Answer 7

one

Question 8

Temperature:

Answer 8

Warmer gases transmit waves faster

Question 9

factors that affect wave speed

Answer 9

temp, properties of the material, (in a string) linear density and tension

Question 10

Very ______ strings transmit energy more
effectively.

Answer 10

tight

Question 11

_____ _______ strings also transmit wave
energy more effectively.

Answer 11

Less dense

Question 12

The linear density, or mass per unit
distance, determines how much _____ it
will take to make the string _______.

Answer 12

force; vibrate

Question 13

_______ 🡪 Energy that travels as
longitudinal waves. Some parts have
high pressure and some parts have low
pressure.

Answer 13

Sound

Question 14

The source of every sound is a _________ ________.

Answer 14

vibrating object

Question 15

in a human voice, what is the vibrating object

Answer 15

vocal chords vibrate

Question 16

in a guitar, what is the vibrating object

Answer 16

strings on the guitar vibrate

Question 17

Sound waves need to travel through a
_________ like air. Therefore, there is no
sound in space!

Answer 17

medium

Question 18

Remember that sound travels by making
air molecules move.

This means that the speed of sound is limited by how fast the molecules can move, which is related to the temperature and density of the medium.

If we ________ the temperature of the molecules, the speed of sound should ________ also.

Answer 18

increase; increase

Question 19

The speed of sound is also effected by
the ______.

Answer 19

medium

Question 20

Sound travels most rapidly
in certain ______, less rapidly in many
______, and quite slowly in most _____.

Answer 20

solids; liquids; gases

Question 21

The ratio of the airspeed of an object to the local speed of sound is called a _____ ________.

Answer 21

Mach number

Question 22

Mach Number =

Answer 22

airspeed of object / local speed of sound

Question 23

When an object is travelling at Mach 1, it
is travelling at ____________________

Answer 23

the same speed as sound

Question 24

When an object is travelling at Mach 2, it
is travelling at ____________________

Answer 24

twice the speed of sound

Question 25

The audible region of the sound spectrum for humans is from

Answer 25

20 Hz to 20kHz.

Question 26

Hz means

Answer 26

1/second (1/s)

Question 27

Frequencies lower than 16 Hz are called __________.

Answer 27

Infrasonic

Question 28

Frequencies higher than 20 000 Hz are called ________.

Answer 28

ultrasonic

Question 29

___________ describes how humans perceive sound energy.

Answer 29

Loudness

Question 30

The loudness of a sound wave is based on its _________.

Answer 30

amplitude

Question 31

The larger the amplitude of the wave, the ________ the sound will be.

Answer 31

louder

Question 32

The amplitude of a wave is an indication of how much ________ is being transferred.

Answer 32

energy

Question 33

The amount of sound energy being transferred per unit area is called _______ _________.

Answer 33

sound intensity

Question 34

_______- 🡪 the amount of sound energy passing each second through a unit area.

Answer 34

Intensity

Question 35

Sound intensity is most commonly measured in Bells or _________.

Answer 35

Decibels

Question 36

The intensity of sound _________ as the distance from the source _______.

Answer 36

decreases; increases

Question 37

why are transverse waves called secondary waves?

Answer 37

Transverse waves are called secondary waves because they arrive after the longitudinal wave.

Question 38

predict what happens to the wavelength of a wave on a string when the frequency is doubled. assume that the tension in the string remains the same

Answer 38

The wavelength is halved. The speed stays the same because the tension and linear density remain the same. That means that when the value of f doubles in the equation v = fλ, the value of λ must be divided by two.

Question 39

predict what happens to the speed of a wave on a string when the frequency is doubled. assume that the tension in the string remains the same

Answer 39

The speed is doubled. Given the equation v = fλ, when frequency is doubled, for the left side of the equation to equal the right side, the velocity should also be doubled

Question 40

An aircraft flying at Mach 2 means...

Answer 40

An aircraft flying at Mach 2 means that it is travelling at a speed equal to double the speed of the sound at that temperature

Question 41

explain why the speed of sound varies

Answer 41

The speed of sound varies by temperature and density of the medium, both of which depend on the molecular structure of various particles

Question 42

sound intensity

Answer 42

Sound intensity is a measure of energy per unit area due to a sound wave

Question 43

loudness

Answer 43

Loudness is a measure of the sound intensity. It can also be defined as a human perception of sound energy

Question 44

decibel

Answer 44

The decibel is the unit of measurement of sound level used to describe sound intensity

Question 45

why are different sounds required for sound intensity and loudness

Answer 45

Loudness is expressed in a logarithmic scale using decibels (dB). Decibels are a more convenient measurement unit than watts per square metre (W/m2).

Question 46

describe the concept of sound intensity

Answer 46

Sound intensity is a measure of energy flowing through the unit area due to a sound wave.

Question 47

Vibrations through a gas produce regions where particles are farther apart. What are these regions called? (a) compressions (b) rarefied (c) complex waves (d) rarefactions

Answer 47

(d) rarefactions

Question 48

Which of the following are geometric wave characteristics? (a) waveform, amplitude, and phase shift (b) amplitude, crest, and trough (c) crest, trough, and frequency (d) period, speed, and frequency

Answer 48

(b) amplitude, crest, and trough

Question 49

Infrasonic waves have frequencies (a) below 20 Hz (b) within the range 20 Hz to 20 kHz (c) above 20 kHz (d) within the range 1 kHz to 5.5 kHz

Answer 49

(a) below 20 Hz

Question 50

The Mach number is the ratio of (a) force per unit area (b) airspeed to the local speed of sound (c) loudness to distance (d) pressure to speed

Answer 50

(b) airspeed to the local speed of sound

Question 51

true or false A longitudinal wave is a wave in which particles vibrate in a direction that is perpendicular to the direction of the flow of energy.

Answer 51

false

Question 52

t or f The units of a wave’s phase are the same as the unit of the wavelength.

Answer 52

true

Question 53

t or f Cooler gases are more effective than warmer gases at transmitting sound.

Answer 53

false

Question 54

t or f The amplitude of a longitudinal wave is a difference in pressure.

Answer 54

true