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49 Cards in this Set
- Front
- Back
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What is instantaneous amplitude?
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the amount of displacement in the medium at a particular reference point
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What is peak amplitude
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the distance from the point of rest to the point of maximum displacement
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what is peak to peak amplitude
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the distance from the point of maximum positive displacement to maximum negative displacement
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root mean square amplitude
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the square root of all displacement deviation values squared
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dyne
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the force required to accelerate a mass of 1g from a velocity of 0 cm/sec to a velocity of 1 cm/sec in a second
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how much does velocity lead displacement by?
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90 degrees
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how much are acceleration and displacement out of phase
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180 degrees
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why do we use rms amplitude to measure amplitude of sine waves?
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rms amplitude measures the “effective pressure” of the waveform and best reflects the overall power of the waveform, whereas peak amplitude and peak-peak amplitude or less useful because the amplitude of the signal is more frequently near zero.
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frequency
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the rate in cycles per second at which a vibratory motion repeats itself
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what is the formula for frequencey
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f=1/P (period)
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what is frequency measured in
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H3 (hertz)
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frequency is inversely proportional to what?
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length and mass (the longer the length the slower the frequency; the greater the mass the lower the frequency)
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period
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the amount of time that it takes to complete one cycle of motion
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formula for period
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P=1/F (frequency)
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phase
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that fraction of the period that has elapsed since the vibratory disturbance passed some reference point
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wavelength
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the distance a sound travels in one period
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what is wavelength related to?
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frequency and propagation of speed
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what is the formula for wavelength?
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wavelength=c/f (velocity/frequency)
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as the frequency of sound increases the wavelength of sound...
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deacreases
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for wavelength what are the measurements of frequency in meters and feet?
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344 m/s
1130 ft/s |
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nano
peco kilo mega |
9 to the left
12 to the left 3 to the right 6 to the right |
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why are logarithms important
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the range in sound intensities, in comparison to those sounds who are barely audible (sound thresholds) and those that are painful to the ear
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important log fact
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the log of a number raised to a power equals the power times the log of that number
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what do sound waves transfer
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energy, not substance
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what does the energy transfer vibrate through?
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potential and kinetic forms
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potential and kinetic energy
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potential: stored energy
kinetic: energy of motion |
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energy
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the capacity to do work
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work
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is done when a force acts (does something) through a distance
thus: WORK is FORCE acting through a DISTANCE |
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what is the basic unit of force?
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dyne
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what is the formula for work?
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Work (ergs)=force (dynes) X distance (cm)
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what is the basic unit of work
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ergs
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what is the units of force and work in the MKS system
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force: newton
work: joule |
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newton and joule def.
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newton: the amount of force required to accelerate a 1kg mass from a velocity of 0 to 1m/s in 1 sec
joule: the amount of work done by 1 N acting through a distance of 1m |
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power
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the rate at which work is done
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what is the basic unit of power?
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watt: the power exerted by 10^7 dynes acting through 1cm in 1 sec
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is force enough to describe power?
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NO because infinitely small force could do infinite work in infinite time
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how much does 1 horsepower =
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745 watts
550 feet*lbs/sec |
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what is sound intensity?
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the flow of sound energy as measured in terms of power (work done in some time period) through a given area
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what is the energy flow often measured in?
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watts/m^2
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what is pressure?
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force acting over a given area
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what is the relative threshold of hearing in terms of pressure?
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.00002 dynes/cm^2
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what is intensity proportional to?
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the square of pressure
I=P^2 |
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pressure is proportional to what?
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the square root of intensity
P= sqrt(I) |
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what is the decibel?
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1/10 of a bell
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what is the decibel formula for intensity?
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dB=10log( I (1)/ I (o))
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what is the standard reference intensity?
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10 ^ (-12) watts/m^2
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what is the decibel formula for pressure?
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dB= 20log (P (1)/ P (o))
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if you increase sound pressure by 10x then how much will dB go up?
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20 dB
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what is the formula for multiple sources all generating at the same intensity
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dbn(total amt)= dbI (1 intensity level) + 10logX(amt of objects)
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