Q1S1 Ch. 2 Physics - Exercises

Front 1

Electromagnetic waves
a) do not transfer energy
b) cannot propagate through a medium
c) include sound waves
d) none of the above

Back 1

d) none of the above

Front 2

Mechanical waves must have a ______ to propagate.

Back 2

medium

Front 3

Sound is a _______ wave.

Back 3

mechanical

Front 4

All waves transport _____.

Back 4

energy

Front 5

A mechanical wave implies an interaction between the wave and the ________.

Back 5

medium

Front 6

If a wave needs a medium to propagate, it is a _____ wave.

Back 6

mechanical

Front 7

If a wave does not need a medium to propagate, it is an ___ wave.

Back 7

electromagnetic

Front 8

Which of the following is not an example of an electromagnetic wave?
a) x-rays
b) light
c) sound
d) heat
e) television signals

Back 8

c) sound (sound is a mechanical wave)

Front 9

All waves are a(n) ______transfer most often through cyclical variations.
a) particle
b) energy
c) voltage
d) temperature

Back 9

b) energy (waves are an energy transfer through cyclical variations)

Front 10

The naming of waves as mechanical is due to the physical interaction between the wave & the medium. The interaction produces 4 specific possible changes call acoustic variables:

Back 10

pressure
density
temperature
distance

Front 11

All of the following are acceptable units of pressure except:
a) Pa
b) lb/in squared
c) kg/m squared
d) lb/ft
e) atm (atmospheres)
f) mmHg (millimeters of mercury)

Back 11

d) lb/ft (pressure is a force per area - lb/ft is a force per distance)

Front 12

Density is defined as:
a) mass volume, kg/m cubed
b) mass/volume, kg/m squared
c) volume/mass, m cubed/kg
d) mass X volume, m cubed kg

Back 12

a) mass/volume, kg/m cubed

Front 13

Sound is a _____, _____ wave.
a) longitudinal, electromagnetic
b) longitudinal, mechanical
c) transverse, electromagnetic
d) transverse, mechanical

Back 13

b) longitudinal, mechanical

Front 14

For a longitudinal wave, the energy is transported by a series of _ and __ of the medium particles.
a) compression, heating
b) rarefactions, reflections
c) reflections, refractions
d) compressions, rarefactions

Back 14

d) compressions, rarefactions

Front 15

Repetitious waves are a _____ transfer of ___________.

Back 15

cyclical, energy

Front 16

Cyclical means
a) periodic or repetitive
b) in a circle
c) linear

Back 16

a) periodic or repetitive

Front 17

The major classifications of waves are

Back 17

mechanical
electromagnetic

Front 18

An electromagnetic wave does not need a ___ to propagate.

Back 18

medium

Front 19

Examples of electromagnetic waves are
a) TV, microwave, sound
b) music, ultrasound, and ocean waves.
c) x-rays, light, and microwaves

Back 19

c) x-rays, light, and microwaves.

Front 20

A ________ wave needs a medium to propagate.

Back 20

mechanical

Front 21

There can be no ________waves in a vacuum.

Back 21

mechanical

Front 22

A vacuum is the absence of a

Back 22

medium.

Front 23

There is no sound in a _____, since there is no medium.

Back 23

vacuum

Front 24

Two classifications of mechanical waves are

Back 24

transverse and longitudinal

Front 25

In a ___ wave, particle motion is perpendicular or "transverse" to the wave directions.

Back 25

transverse

Front 26

In a _______ wave, the particle motion is back and forth in the same direction as the wave propagation.

Back 26

longitudinal

Front 27

Sound is _____, mechanical wave.

Back 27

longitudinal

Front 28

A longitudinal wave has areas of ______ and compression.

Back 28

rarefaction

Front 29

An area of ______ is where the particles are farther apart than the normal state.

Back 29

rarefaction

Front 30

An area of ______is where the particles are closer together than the normal state.

Back 30

compression

Front 31

Not all waves need a ____ to propagate; _____ waves can operate in a vacuum.

Back 31

medium, electromagnetic

Front 32

__________ is a way of specifying how fast a wave is cyclically varying.

Back 32

Frequency

Front 33

The unit for frequency is ____, which is an abbreviation for cycles per __________.

Back 33

Hz, second

Front 34

Frequency has units which are the inverse of ________, or one divided by ________, also call Hz.

Back 34

time, second

Front 35

The number of times a longitudinal wave reaches maximum compression and rarefaction per time is called the ___________.

Back 35

period

Front 36

The reciprocal of frequency is the______

Back 36

period

Front 37

The period has units of

Back 37

time

Front 38

The reciprocal of the ______is frequency. Frequency has units of Hertz.

Back 38

period

Front 39

The ________ is the time between cycles of peak compression in a longitudinal wave, such as sound.

Back 39

period

Front 40

The ________ between cycles of peak compression is the same as the time between cycles of peak rarefaction

Back 40

time

Front 41

The ______ is the _________ between cycles of peak rarefaction

Back 41

period, time

Front 42

Frequency and period are _____.

Back 42

reciprocals

Front 43

The units for _____ and period are reciprocals.

Back 43

frequency

Front 44

Hertz and _______ (or seconds) are inversely related.

Back 44

time

Front 45

Since frequency and period are inversely related, if the frequency increases the period __________.

Back 45

decreases

Front 46

A shorter period means a higher ________.

Back 46

frequency

Front 47

A lower ___________ means a longer period.

Back 47

frequency

Front 48

The _______ is the physical measure of distance between wave peaks (maxima) or similarly wave (minima).

Back 48

wavelength

Front 49

Wavelength is a measure of ______ and therefore in the metric system has units of ___.

Back 49

distance, meters

Front 50

The period is a measure of ____ between peaks whereas the _______ is a measure of distance between peaks.

Back 50

time, wavelength

Front 51

Frequency and _______ are related throught the wave propagation velocity.

Back 51

wavelength

Front 52

The propagation _____ has units of m/sec.

Back 52

speed or velocity

Front 53

The __________ _______ is a measure of how fast a wave will travel.

Back 53

propagation speed

Front 54

The propagation velocity, (c), equals the frequency, (f), times the _________.

Back 54

wavelength

Front 55

For a given propagation velocity, if the frequency increases, the ______ must decrease.

Back 55

wavelength

Front 56

For a given propagation velocity, if the frequency _____, the ______ must increase.

Back 56

decreases, wavelength

Front 57

Frequency and wavelength have an _____relationship.

Back 57

inverse

Front 58

If the propagation velocity changes and the frequency is not changed the ___ must change.

Back 58

wavelength

Front 59

To determine the _____, the frequency and the propagation speed must be known.

Back 59

wavelength

Front 60

The frequency, wavelength and propagation speed are related together by the equation...

Back 60

wavelength = propagation speed / frequency

Front 61

The _______ of a signal is a measure of how big or loud it is.

Back 61

amplitude

Front 62

The _________ is determined as the maximum variation from the mean.

Back 62

amplitude

Front 63

The ________ is the same as the average.

Back 63

mean

Front 64

The ____ = maximum + minimum/ 2

Back 64

mean

Front 65

If the maximum is 20 and the minimum is 10, the mean is _

Back 65

15

Front 66

The difference between the max and the mean is the same as the difference between the mean and the ?

Back 66

minimum

Front 67

Since the amplitude equals the difference between the maximum and the mean, the ____ also equals the difference between the ____ and the minumum.

Back 67

amplitude, mean

Front 68

Amplitude is used to measure any wave variable. For sound waves, the units of amplitude will be any measure of the four ___ variables.

Back 68

acoustic

Front 69

A wave which has a physical interaction with the ______ is called a mechanical wave.

Back 69

medium

Front 70

A change within the ______ caused by a wave is a called a variable.

Back 70

medium

Front 71

For an acoustic wave, the changes caused to the medium are called ______ variables.

Back 71

acoustic

Front 72

There are ____ acoustic variables.

Back 72

4

Front 73

The four acoustic variables are:

Back 73

pressure
density
distance ( particle displacement)
temperature

Front 74

Units of _____ are: Pascals, Atmospheres, mmHg, kg/m squared, lbs/ in squared

Back 74

pressure

Front 75

Units of __________ are: meters feet, miles, yards, etc.

Back 75

distance

Front 76

Units of ________ are mass/volume.

Back 76

density

Front 77

Changes in acoustic variables are the result of the mechanical interaction of the acoustic wave and the ____.

Back 77

medium

Front 78

What is the frequency, in Hz, of something that occurs 60 times in one minute?

Back 78

60 times/1 minute =
60 times/ 60 seconds =
1 time / 1 second =
1 Hz

Front 79

What is the frequency, in Hz, of something that occurs 60 times in 0.5 seconds?

Back 79

60 times / 0.5 sec =
120 times / 1 sec =
120 Hz

Front 80

What is the frequency, in Hz, of something that occurs 60 times in 0.1 seconds?

Back 80

60 times / 0.1 sec =
600 times / 1 sec =
600 Hz

Front 81

What is the frequency, in Hz, of something that occurs 60 times in 1 hour?

Back 81

Since 1 hour = 60 minutes = 3600 seconds:
60 times/ 1 hour =
60 times/ 3,600 sec =
1/60 Hz

Front 82

What determines the frequency of operation for ultrasound?
a) medium
b) pulser
c) patient
d) wavelength

Back 82

b) pulser

Front 83

How much will the frequency change if the propagation speed changes by a factor of 2?

Back 83

Frequency will not change. Frequency is determined by by the source, not the properties of the medium.

Front 84

If the frequency is 1 MHz, what is the period?

Back 84

period = 1/ frequency
1/1 MHz =
1 usec

Front 85

If the period is 0.5 useconds, what is the frequency/

Back 85

frequency = 1/period
1 / 0.5 usec =
1 / 0.5 MHz =
2 MHz

Front 86

Which two of the following give the same info?
1) frequency = 10 kHz
2) frequency = 3 kHz
3) period = 0.1 msec
4) period = 10 ksec

Back 86

1 and 3
A 10 kHz frequency = a 0.1 msec period.

Front 87

Since the period and the frequency are reciprocals, the period multiplied by the frequency equals __.

Back 87

one

Front 88

What determines the period for ultrasound?
a) medium
b) pulser
c) patient
d) wavelength

Back 88

b) pulser

Front 89

How much will the period change if the propagation velocity changes by a factor of 2?

Back 89

The period will not change.

Front 90

If ultrasound travels 662 meters through air in 2 seconds, what is the propagation speed of sound in air in m/sec?

Back 90

331 m/sec

Front 91

How far can a car travel in 2 hours driving at 60 mph?

Back 91

120 mph

Front 92

How far can an ultrasound beam travel in soft tissue in 1 second?

Back 92

1540 m/sec

Front 93

How long would it take a car traveling 30 mph to travel 45 miles?

Back 93

1.5 hours

Front 94

How long would it take ultrasound in soft tissue to travel to a target 1 cm deep and back to the transducer?

Back 94

1540 m/sec or 13usec

Front 95

The speed of sound
a) changes w/ frequency
b) changes w/ period
c) depends on inertia and elasticity of medium

Back 95

c