waves and sound Flashcards by Maddi Clark

periodic motion

movement of waves where they displace from 0 in a cyclic fashion

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amplitude

displacement from 0 to highest point

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period of motion

time T it takes to get to adjacent peaks

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frequency

1/T, amont of peaks in a given amount of time
unit: hertz

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phase difference

two objects in same period motion that have the same frequency but are out of sync
- visualized by the time difference between x intercepts on graphs of their motion

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at peak of peridoic movment what is the velocity

0, and PE is at its highest

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potential energy for a pendulum

mgh

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potential energy for a spring

1/2kx^2

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when is the KE highest for periodic motion

when y=o
1/2mv^2

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what force keeps periodic motion stable

restoring force that trys to pull objects back to equillibrium point

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restoring force of spring

-kx

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restoring force of pendulum

mg (gravity)

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equation for calculating the period of a spring

T= 2π/ sqrt(m/k)

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what does a large T mean for frequency

low frequency

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eqn for period of a pendulum

T = 2π/sqrt(L/g)

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period, time for a cycle of motion to repeat

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mechanical waves

involve actual physical motion of particles
can be transverse or longitudinal

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transverse waves

particles move perpendicular to the axis of the wave
- move through water

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longitudinal waves

particles move parralel to axis of wave
- move in sam direction of wave

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propagation speed

speed that a wave moves through space –> depends on medium

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units of Frequency

Htz or 1/s

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propagation speed of wave eqn

v= f* λ
- λ is wavelength
- f is frequency

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speed of light eqn

c = λ *f
c= 3.0E8 m/s

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what happens to the frequency and wavelength of a wave when it passes through a new medium

frequency REMAINS THE SAME but wavelength changes with the medium

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what is associated with higher speed of propogation

higher wavelength

interference

amplitidue of waves at a given location will add together to predict their behavior

constructive interference

overlapping waves have the same amplitude with the same directionality they add together to be greater than either of the components - ammplitdues will add linearly to 2y

destructive interference

overlapping waves have amplitudes with opposite directionality and cancel out y-y = 0 if they have the exact same amplitude

sound waves

longitudinal and compressed and we experience sound through pressure

pressure eqn

force/ area

what kind of material does sound move faster throgh

non-compressible or stiff mediums

bulk modulus

vsound = sqrt(b/p) degree that material resists compression - speed of sound depends on density and resistance to compressibility - presssure needed to compress a substance - high b value = high resistance to compressibility

what phase of matter has the highest bulk modulus

solids

which phase of matter does sound move through the fastest

solids, then liquids, then gases

intensity of sound

power delivered over a given area W/m^2

loudness

how intensity is percieved by ear. not same thing as intensity

intensity is preporitional to what

the amplitude squared

units of intensity

W/m^2 or Db

decible scale

logarithmic , 12 orders of magnitude from 1.0E-12 W/m^2 to 1 W/m^2

intensity ratio of sound in decibles

dB= 10log (I/Io) I is intensity of light Io is (1.0E-12) ratio is from 120-130 dB

attenuation of sound

decreases as distance increases

what quality is attributed to amplitdue of a sound wave

loudness

what quality is attributed to frequency of soundwave

pitch of sound - increased frequency= higher pitch

human range of pitch

20 hZ to 20 kHz

doppler effect

an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move toward (or away from) each other. The effect causes the sudden change in pitch noticeable in a passing siren, as well as the redshift seen by astronomers.

according to doppler, the closer the source of sound

the higher frequency

doppler equation

F0 = Fs ( v + vo)/(v+vs) - fo is observer frequency of sound - Fs is frequency of source v is speed of sound vo is speed of observer vs is speed of source

when is the velocity of the observer positive

when observer is moving toward the source

when is v source considered positive

when source is moving away from observer

doppler eqn: when the numerator is greater than the denominator what happens?

frequency increases for observer

doppler eqn: when the demoninator is greater than the numerator what happens

frequency decreases for observer

ultrasound imaging

use high sound frequencies to image structures of body

doppler ultrasoundography

frequency shifts are utilized to determine whether blood is flowing to or away from the transducer - calculate velocity of blood moving through a vessel

standing wave

stable patterns of interference among waves propagating in opposite directions - wavelike product of multiple waves

shape of standing wave graph

sigmoidal, areas with no displacement are like y=0

points of a standing wave with 0 displacement

nodes

points of a standing wave with maximum displacement

antinodes

common mediums that support standing waves

1. PIPE 2. TAUT STRINGS

taut strings

held tight and cannot vibrate, so the ends of the strings are nodes , and increaseing the amount of antinodes in between will increase the frequency

first harmonic of a taut string

lowest possible frequency with only 1 node at one end

second harmonic of a taut string

2 antinodes

third harmonic of a taut string

3 antinodes

wavelength formula of the nth harmonic of string

λ = 2/n (L)

frequency formula for the nth harmoic of string

f= n/2 (v/L)

pipes

closed ends: nodes open ends: antinodes

wavelength formula for the nth harmonic of a pipe with 2 open ends

λ= 2L/n

difference between pipes and strings for nth harmonics

nth for strings refers to how many antinodes the string has nth for open pipes refers to how many nodes the pipe has

pipe with one closed end and one open end

closed end is a node open end is an antinode

wavelength formula for the nth harmonic with a closed end

λ = 4L/ n (odd) - only works for odd number of nodes

wavelength formula for the nth harmonic with a closed end

λ = 4L/ n (odd) - only works for odd number of nodes

frequency formula for the nth harmonic with a closed end

f = n(odd)/4 *v/L

wavelength fromula for nth harmonic with open ends

λ= 2n/L

frequency formula for the nth harmonic with open ends

f= n/2*V/L - antinodes on open ends

what are the ends of a 2 open pipe

antinodes

what are the ends of a pipe that is closed

closed end is node, open is antinode