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Physics 11 > Wave Speed and Sound > Flashcards

Wave Speed and Sound Flashcards

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1
Q

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

A

frequency

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2
Q

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

A

source; source

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3
Q

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

A

never

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4
Q

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

A

period; inverse

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5
Q

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

A

Speed

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6
Q

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

A

cycle; period

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7
Q

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

A

one

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8
Q

Temperature:

A

Warmer gases transmit waves faster

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9
Q

factors that affect wave speed

A

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

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10
Q

Very ______ strings transmit energy more
effectively.

A

tight

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11
Q

_____ _______ strings also transmit wave
energy more effectively.

A

Less dense

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12
Q

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

A

force; vibrate

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13
Q

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

A

Sound

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14
Q

The source of every sound is a _________ ________.

A

vibrating object

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15
Q

in a human voice, what is the vibrating object

A

vocal chords vibrate

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16
Q

in a guitar, what is the vibrating object

A

strings on the guitar vibrate

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17
Q

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

A

medium

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18
Q

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.

A

increase; increase

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19
Q

The speed of sound is also effected by
the ______.

A

medium

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20
Q

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

A

solids; liquids; gases

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21
Q

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

A

Mach number

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22
Q

Mach Number =

A

airspeed of object / local speed of sound

23
Q

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

A

the same speed as sound

24
Q

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

A

twice the speed of sound

25
Q

The audible region of the sound
spectrum for humans is from

A

20 Hz to 20kHz.

26
Q

Hz means

A

1/second (1/s)

27
Q

Frequencies lower than 16 Hz are called
__________.

A

Infrasonic

28
Q

Frequencies higher than 20 000 Hz are
called ________.

A

ultrasonic

29
Q

___________ describes how humans
perceive sound energy.

A

Loudness

30
Q

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

A

amplitude

31
Q

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

A

louder

32
Q

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

A

energy

33
Q

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

A

sound intensity

34
Q

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

A

Intensity

35
Q

Sound intensity is most commonly
measured in Bells or _________.

A

Decibels

36
Q

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

A

decreases; increases

37
Q

why are transverse waves called secondary waves?

A

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

38
Q

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

A

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.

39
Q

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

A

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

40
Q

An aircraft flying at Mach 2 means…

A

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

41
Q

explain why the speed of sound varies

A

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

42
Q

sound intensity

A

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

43
Q

loudness

A

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

44
Q

decibel

A

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

45
Q

why are different sounds required for sound intensity and loudness

A

Loudness is expressed in a logarithmic scale
using decibels (dB).

Decibels are a more convenient measurement unit than watts per square metre (W/m2).

46
Q

describe the concept of sound intensity

A

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

47
Q

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

A

(d) rarefactions

48
Q

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

A

(b) amplitude, crest, and trough

49
Q

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

A

(a) below 20 Hz

50
Q

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

A

(b) airspeed to the local speed of sound

51
Q

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.

A

false

52
Q

t or f

The units of a wave’s phase are the same as the unit of the wavelength.

A

true

53
Q

t or f

Cooler gases are more effective than warmer gases at transmitting sound.

A

false

54
Q

t or f

The amplitude of a longitudinal wave is a difference in pressure.

A

true

Physics 11 (30 decks)

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