# Shared Flashcard Set

## Details

Chapter 15
Sound
35
Physics
02/20/2013

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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