Physics #7

Question 1

transverse waves

Answer 1

those in which the direction of particle oscillation is perpendicular to propagation of the wave
Ex: wave in a stadium: moves around stadium but people just go up and down.
Ex: string whipped up and down attached at one point.

Question 2

longitudinal waves

Answer 2

the particles of the wave oscillate parallel to the direction of propagation
Ex: person pushing in and pulling out a piston
Ex: slinky on a table and tapping it, kind of bumping into each other as the wave moves down.

Question 3

propagation

Answer 3

movement and direction of energy transfer

Question 4

maximum value of a wave is a ____

Answer 4

crest

Question 5

wavelength

Answer 5

distance from one crest to the next (m)

Question 6

frequency

Answer 6

number of wavelengths passing a fixed point per second (Hz) Cycles/second

Question 7

period

Answer 7

seconds/cycle

Question 8

equilibrium position

Answer 8

the central point around which waves oscillate

Question 9

displacement and amplitude

Answer 9

displacement (x): describes how far a particular point on the wave is from the equilibrium position (expressed as a vector quantity)
amplitude (A): the maximum magnitude of displacement in a wave

Question 10

what is the distance between a crest and trough called?

Answer 10

2x the amplitude

Question 11

trough vs. crest

Answer 11

trough: bottom of the wave
crest: top of the wave

Question 12

phase difference

Answer 12

for waves passing each other, calculating how in step or out of step they are

Question 13

what is the phase difference for 2 waves that completely line up?

Answer 13

0 (360 degrees)

Question 14

what is the phase difference for 2 waves that are completely out of phase?

Answer 14

180 or lambda/2

Question 15

the principal of superposition

Answer 15

when waves interact with each other, the displacement of the resultant wave at any point is the sum of the displacements of the two interacting waves

Question 16

constructive interference

Answer 16

when waves are perfectly in phase, the displacements always add together and the amplitude of the resultant is equal to the sum of the amplitudes of the two waves

Question 17

destructive interference

Answer 17

when waves are perfectly out of phase, the displacements always counteract each other and the amplitude of the resultant wave is the difference between the amplitudes of the interacting waves

Question 18

traveling wave

Answer 18

wave that moves

Question 19

standing wave

Answer 19

the only apparent movement of the string is fluctuation of amplitude at fixed points along the length of the string. In reality the string is moving up and down (slow-mo) but looks like it is just standing there on top and bottom in real time.

Question 20

nodes vs. antinodes

Answer 20

nodes: points in the wave that remain at rest (amplitude is 0)
antinodes: points midway between the nodes fluctuate with maximum amplitude

Question 21

timbre

Answer 21

quality of sound

Question 22

what frequencies are audible to healthy adults

Answer 22

20 Hz to 20,000 Hz

Question 23

what produces the richest sounds

Answer 23

when objects vibrate at multiple natural frequencies (a fundamental pitch and multiple overtones) that are related to each other by whole number ratios.

Question 24

the amplitude of wave increases if the ______ is nearly identical to the natural frequency

Answer 24

forced frequency

Question 25

if the frequency of the periodic force is equal to a natural/resonant frequency of the system, then the system is said to be ______, and the amplitude of oscillation is at a maximum

Answer 25

resonating

Question 26

damping/attenuation

Answer 26

a decrease in amplitude of a wave caused by an applied or nonconservative force.

Question 27

what are the units for angular frequency

Answer 27

radians per second

Question 28

wave speed

Answer 28

rate at which a wave transmits the energy or matter it is carrying

Question 29

standing wave vs. traveling wave

Answer 29

traveling wave has nodes and antinodes that move with propagation standing wave: nodes and antinodes do not move

Question 30

are sound waves longitudinal or transverse waves?

Answer 30

longitudinal

Question 31

applying a force at the natural frequency of a system will cause the system to _____

Answer 31

resonate | increases the amplitude of oscillations

Question 32

can sound travel through the following: solids, liquids, gases, vaccum?

Answer 32

everything but vacuum because it needs deformable medium.

Question 33

bulk modulus

Answer 33

a measure of a medium's resistance to compression

Question 34

how does the bulk modulus relate to solids, liquids, and gases

Answer 34

increases from gases to solids

Question 35

what is the speed of sound in air at 20 degrees Celsiucs?

Answer 35

343 m/s

Question 36

what medium and density is the speed of sound the fastest in?

Answer 36

solid with very low density

Question 37

pitch

Answer 37

our perception of the frequency of sound

Question 38

infrasonic vs. ultrasonic waves

Answer 38

infrasonic: less than 20 Hz ultrasonic: more than 20,000 Hz

Question 39

doppler effect

Answer 39

describes the difference between the actual frequency of a sound and its perceived frequency when the source of the sound and the sound's detector are moving relative to one another.

Question 40

echolocation and doppler

Answer 40

the sound bounces off of a surface and is reflected back to the animal. How long it takes to return and the change in frequency of the sound can be used to determine the position of objects in the environment and the speed at which they are moving.

Question 41

in the doppler effect equation, if the detector or the source is not moving, then _______

Answer 41

the numerator or denominator is just the speed of the sound in the medium.

Question 42

shock wave

Answer 42

speed of object is greater than speed of sound. Pressure difference created that can be detrimental to the other objects that it passes through

Question 43

what are other words for loudness or volume of sound?

Answer 43

intensity

Question 44

intensity

Answer 44

average rate of energy transfer per area across a surface that is perpendicular to the wave power/area (w/m^2)

Question 45

what is the surface area of a sphere

Answer 45

4(pi)r^2 | useful for knowing distance traveled and area covered for a sound wave

Question 46

what is the minimum intensity of hearing and the threshold of pain?

Answer 46

min: 1x10^-12 W/m^2 pain: 10 W/m^2

Question 47

attenuation affects _____, ____ and ____, but not ______

Answer 47

amplitude, intensity, sound level | not frequency

Question 48

how can sound volume vary due to interference effects?

Answer 48

beat frequency when two pitches are produced next to each other.

Question 49

the points in a standing wave with no fluctuation in displacement are called ____

Answer 49

nodes

Question 50

the points in standing waves with maximum fluctuation are called _____

Answer 50

antinodes

Question 51

closed vs. open boundaries

Answer 51

closed: nodes open: maximal oscillation

Question 52

fundamental frequency of strings attached at both ends or open pipes

Answer 52

the first harmonic | the lowest frequency (longest wavelength) of a standing wave that can be supported by a given length of string

Question 53

first overtone of strings attached at both ends or open pipes

Answer 53

n=2

Question 54

n= 3 is known as the _____ for strings attached at both ends or open pipes

Answer 54

second overtone or third harmonic

Question 55

for strings attached at both ends, the number of antinodes present will tell you the _____

Answer 55

harmonic | or number of half wavelengths = harmonic

Question 56

for open pipes, the number of nodes will tell you ______

Answer 56

the harmonic

Question 57

the harmonic in a closed pipe is equal to the number of ______

Answer 57

quarter wavelengths supported by the pipe

Question 58

closed pipe

Answer 58

open at one end and closed on the other

Question 59

ultrasound

Answer 59

uses high frequency sound waves outside the range of human hearing to compare the relative densities of tissue in the body uses speed pf the wave and travel time to generate a graphical representation of borders and edges within the body by calculating the traversed distance.

Question 60

doppler ultrasound

Answer 60

used to determine the flow of blood within the body by detecting the frequency shift that is associated with movement toward or away from the receiver

Question 61

how is sound produced?

Answer 61

mechanical vibrations

Question 62

to which properties of sound do amplitude and frequency correspond?

Answer 62

intensity (sound level) and pitch

Question 63

if object and source are moving in same direction at same speed what is the perceived frequency compared to the actual frequency?

Answer 63

equal

Question 64

____ is the increase in amplitude that occurs when a periodic force is applied at the natural (resonant) frequency of an object

Answer 64

resonance

Question 65

shock waves are largest when ____

Answer 65

the objet is traveling at exactly the speed of sound