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Chapter 15
Sound
35
Physics
12th Grade
02/20/2013

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Term
What type of wave is a sound wave?
Definition
longitudinal/mechanical
Term
since a sound wave is a mechanical wave, it must do what?
Definition
go through a medium
Term
What are the three parts of the sonic spectrum?
Definition
infrasonic, audio portion, ultrasonic
Term
What is the range of frequencies that humans can hear?
Definition
20 to 20,000 hz
Term
In what type of medium does sound travel the fastest?
Definition
solid
Term
How do you determine the speed of sound in air?
Definition
V=331.5 + .6T
Term
Harmonic content is heard as _____.
Definition
quality
Term
How do humans perceive intensity?
Definition
loudness
Term
HOw do you calculate the sound or relative intensity of a sound (loudness)?
Definition
B= 10 log I/Io
Term
What is the value of Io?
Definition
10 to the -12 w/m squared
Term
What is the unit of relative intensity?
Definition
decibel
Term
How does the ear hear frequency?
Definition
pitch
Term
How do you calculate the perceived frequency using the doppler equation?
Definition
fp=fs (V+Vo/V-Vs)
Term
What is the doppler effect?
Definition
apparent shift in frequency due to motion between the listener and the source
Term
HOw does the pitch change if the listener and source are getting closer together? Farther apart?
Definition
closer-ptich is higher; farther-pitch is lower
Term
What term is given to the lowest frequency a vibrating string can produce?
Definition
fundamental frequency (f1)
Term
What is the relationship between the length of the string and the wavelength of the fundamental?
Definition
wavelength=2l or length=1/2wavelength
Term
What are harmonics?
Definition
whole number multiples of the fundamental frequency
Term
What is the relationship between the length of a closed pipe and the wavelength of the fundamental frequency?
Definition
wavelength=1/4(l +.4d)
Term
What harmonics can a closed pipe produce?
Definition
1st, 3rd, 5th
Term
What is the relationship between the length and wavelength of the fundmanetal for an open pipe?
Definition
length=1/2wavelength
Term
What harmonics can an open pipe produce?
Definition
all harmonics
Term
What is the quality of sound?
Definition
the number of harmonics present and their relative intensities
Term
When do frequencies sound good together?
Definition
when they reduce down to a small whole number ratio, close together numbers (4/5, 1/2, etc.)
Term
What are beats?
Definition
amplitude pulsations when 2 frequencies are close together
Term
If one frequency of 278 hz is played at the same time as 281 hz, how many beats will be heard?
Definition
281-278=3
Term
What determines the speed of sound in a medium?
Definition
the elasticity and density of the medium
Term
What is intensity?
Definition
the rate of energy flow though a unit area
Term
Do we hear all frequncies with equal intensities?
Definition
no, sounds of higher intensity are usually louder but sounds of high frequency may not seem as loud as a sound of low frequency of equal intensity
Term
When is a shock wave formed?
Definition
if teh source is moving higher than the wave
Term
when is the velocity of the observer zero?
Definition
when they arent moving
Term
When is the velocity of teh observer positive or negative?
Definition
it is positive if the observer moves toward the source and negative if teh observer moves away from the source
Term
How does an oscilloscope display a sound wave?
Definition
as a transverse wave
Term
_____is when a vibrating object can cause a second object with the same natural frequency to vibrate with a large amplitude.
Definition
resonance
Term
go over all problems
Definition
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