Ch. 7: Waves and Sound

Question 1

which direction do particles oscillate in transverse waves

Answer 1

perpendicular to the direction of propagation

rope

Question 2

which direction do particles oscillate in longitudinal waves

Answer 2

parallel to the direction or propagation

springs

Question 3

wavelength (gamma)

Answer 3

distance from one maximum of the wave to the next

Question 4

frequency (f)

Answer 4

of wavelengths passing though a point per second

Question 5

unit of frequency

Answer 5

Hz

Question 6

propagation speed equation

Answer 6

v = f*gamma

propagation speed = frequency * wavelength

Question 7

period (T) equation

Answer 7

Number of seconds per cycle. The inverse of frequency.

T = 1/f

Question 8

angular frequency (w) units

Answer 8

radians per second

Question 9

angular frequency (w) equation

Answer 9

w = 2pif = [2*pi] / T

Question 10

amplitude (A)

Answer 10

maximum magnitude of displacement (from the equilibrium position) in a wave

Question 11

phase difference

Answer 11

a measure of how “in step” or “out of step” waves are from each other

Question 12

constructive interference

Answer 12

when waves are perfectly in phase … the resultant wave amplitude is equal to the SUM of the displacement of the two interacting waves

A + A = 2A

Question 13

destructive interference

Answer 13

when waves are perfectly out of phase … resultant wave amplitude is equal to the DIFFERENCE of the displacement of the two interacting waves (zero)

A - A = 0

Question 14

partially constructive/destructive interference

Answer 14

the mostly additive/subtractive effect of waves that are mostly in/out of phase with each other on the resultant wave

Question 15

traveling waves

Answer 15

a wave that propagates with interference between the incident and reflected waves makes wave makes wave appears to move through the medium or be nonexistent

nodes/antinodes move with propagation

Question 16

standing wave

Answer 16

a wave that propagates with interference that makes the wave appear stationary

nodes/antinodes are fixed

Question 17

nodes

Answer 17

points in a wave where amplitude is consistently zero and that remain at rest

Question 18

antinodes

Answer 18

points in a wave where amplitude fluctuates between two maximums

Question 19

timbre

Answer 19

quality of the sound determined by the natural frequency/frequencies of the object

Question 20

forced oscillation

Answer 20

frequency of force applied to system = frequency of a system’s resultant drive

push on a swing = movement of a swing

Question 21

damping/attenuation

Answer 21

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

Question 22

resonance

Answer 22

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

Question 23

sound is what kind of wave

Answer 23

a longitudinal wave

particles move parallel to propagation

Question 24

equation for speed of sound

Answer 24

v = sq root(B/p)

speed = square root of (bulk modulus of medium * density of medium)

Question 25

in what kinds of matter does speed travel fastest and slowest

Answer 25

fastest in solid slowest in gas

Question 26

pitch

Answer 26

perception of the frequency of a sound

Question 27

infrasonic waves

Answer 27

sound waves with frequencies below 20Hz

Question 28

ultra sonic waves

Answer 28

sound waves with frequencies above 20,000 Hz

Question 29

Doppler Effect

Answer 29

difference between perceived and actual frequency of a sound

Question 30

when is perceived frequency greater than actual frequency

Answer 30

when source and object move toward each other

Question 31

when is perceived frequency less than actual frequency

Answer 31

when source and object move away from each other

Question 32

Doppler effect equation

Answer 32

f' = f [ (v +/- vd) / (v -/+ vs) ] top for toward bottom for away

Question 33

shock wave

Answer 33

highly condensed wave front causing physical disturbances in the objects it passes through

Question 34

when can a sonic boom be heard

Answer 34

any time an object moving faster than the speed of sound passes a detector

Question 35

loudness/volume

Answer 35

perception of a wave's intensity

Question 36

intensity

Answer 36

average rate of energy transfer per area across a surface perpendicular to the wave

Question 37

intensity equation with units

Answer 37

I = P/A Watts/square meter

Question 38

closed boundaries

Answer 38

boundaries that do not allow for oscillation and correspond to nodes

Question 39

open boundaries

Answer 39

boundaries that allow for oscillation and correspond to antinodes

Question 40

equation relating string/open pipe length to wavelength

Answer 40

gamma = 2L / n harmonic is an EVEN integer

Question 41

harmonic for strings

Answer 41

how many half wavelengths are supported by the string (number of antinodes present)

Question 42

fundamental frequency

Answer 42

lowest frequency/longest wavelength that can be supported by a given length of string

Question 43

harmonic for open pipes

Answer 43

how many half wavelengths are supported by the pipe | number of nodes present

Question 44

equation relating closed pipe length to wavelength

Answer 44

gamma = 4L/n harmonic is an ODD integer

Question 45

harmonic for closed pipe

Answer 45

how many quarter wavelengths are supported by the pipe