Ch. 7: Waves and Sound Flashcards
which direction do particles oscillate in transverse waves
perpendicular to the direction of propagation
rope
which direction do particles oscillate in longitudinal waves
parallel to the direction or propagation
springs
wavelength (gamma)
distance from one maximum of the wave to the next
frequency (f)
of wavelengths passing though a point per second
unit of frequency
Hz
propagation speed equation
v = f*gamma
propagation speed = frequency * wavelength
period (T) equation
Number of seconds per cycle. The inverse of frequency.
T = 1/f
angular frequency (w) units
radians per second
angular frequency (w) equation
w = 2pif = [2*pi] / T
amplitude (A)
maximum magnitude of displacement (from the equilibrium position) in a wave
phase difference
a measure of how “in step” or “out of step” waves are from each other
constructive interference
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
destructive interference
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
partially constructive/destructive interference
the mostly additive/subtractive effect of waves that are mostly in/out of phase with each other on the resultant wave
traveling waves
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
standing wave
a wave that propagates with interference that makes the wave appear stationary
nodes/antinodes are fixed
nodes
points in a wave where amplitude is consistently zero and that remain at rest
antinodes
points in a wave where amplitude fluctuates between two maximums
timbre
quality of the sound determined by the natural frequency/frequencies of the object
forced oscillation
frequency of force applied to system = frequency of a system’s resultant drive
push on a swing = movement of a swing
damping/attenuation
decrease in an amplitude of a wave caused by an applied/nonconservative force
resonance
increase in amplitude that occurs when a periodic force is applied at the natural (resonant) frequency of an object
sound is what kind of wave
a longitudinal wave
particles move parallel to propagation
equation for speed of sound
v = sq root(B/p)
speed = square root of (bulk modulus of medium * density of medium)
in what kinds of matter does speed travel fastest and slowest
fastest in solid
slowest in gas
pitch
perception of the frequency of a sound
infrasonic waves
sound waves with frequencies below 20Hz
ultra sonic waves
sound waves with frequencies above 20,000 Hz
Doppler Effect
difference between perceived and actual frequency of a sound
when is perceived frequency greater than actual frequency
when source and object move toward each other
when is perceived frequency less than actual frequency
when source and object move away from each other
Doppler effect equation
f’ = f [ (v +/- vd) / (v -/+ vs) ]
top for toward
bottom for away
shock wave
highly condensed wave front causing physical disturbances in the objects it passes through
when can a sonic boom be heard
any time an object moving faster than the speed of sound passes a detector
loudness/volume
perception of a wave’s intensity
intensity
average rate of energy transfer per area across a surface perpendicular to the wave
intensity equation with units
I = P/A
Watts/square meter
closed boundaries
boundaries that do not allow for oscillation and correspond to nodes
open boundaries
boundaries that allow for oscillation and correspond to antinodes
equation relating string/open pipe length to wavelength
gamma = 2L / n
harmonic is an EVEN integer
harmonic for strings
how many half wavelengths are supported by the string (number of antinodes present)
fundamental frequency
lowest frequency/longest wavelength that can be supported by a given length of string
harmonic for open pipes
how many half wavelengths are supported by the pipe
number of nodes present
equation relating closed pipe length to wavelength
gamma = 4L/n
harmonic is an ODD integer
harmonic for closed pipe
how many quarter wavelengths are supported by the pipe
