(_14)+Waves+and+Sound

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The nature of waves: Mechanical Waves Non- Mechanical Waves Longitudinal Waves Transverse Waves [] -slinky || -rope, tightly coiled slinky -"The Wave" ||
 * A wave is a traveling disturbance
 * A wave carries energy from place to place
 * require a medium to propogate
 * do no require a medium to propogate
 * particle motion is in the same direction as the waves motion (direction of propogation)
 * particle motion is perpendicular to the direction of the wave propogated
 * || longitudinal || transverse ||
 * Mechanical || -sound
 * Non-Mechanical || NONE || -light ||

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Units: Wavelength= meters Speed of light= 3.08*10^8 meters per second Period= seconds Frequency= 1/seconds= Hz Amplitude= meters

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__Properties of the Speed of Sound__
 * The speed of sound is faster in a solid than in a liquid and faster in a liquid than in a gas. Solid > Liquid > Gas
 * The smaller/lighter the mass of the molecule in gases the faster the speed of sound.
 * The higher the temperature the faster the speed of sound because the molecules travel faster when it is hotter.

__Speed of a Wave__
 * determined by the medium traveled through
 * V=wavelength/period= λf
 * Speed of wave on string=√(T/u) where T= tension of a string and u=linear mass density
 * An object will vibrate at its natural frequency

__Principle of Super Position__

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 * positive amplitude= molecules more compressed, dense
 * speed of sound wave in air is the same for all notes and frequencies, only the wavelength changes

__Two Speakers Producing the Same Sound__ > > [] > This is a picture showing an out of phase wave. The red wave is exactly 180 degrees out of phase with the blue wave. > > A good video depicting the motions of a sound wave and other important qualities of a sound wave is the following: []
 * Δd=d2-d1=path difference between the two sound wave
 * Constructive Interference in phase: Δd=nλ
 * Destructive Interference in phase: Δd=(n+1/2)λ
 * Constructive Interference: When the troughs and peaks of a wave line up to produce an amplified sound
 * Destructive Interference: When the trough of a wave meets with the peak of another wave, sounds cancels out
 * Out of phase: half a cycle off, equations for construcive interference and destructive interference are the same except switched

Wave Problems 1. A sound wave has a frequency of 262 Hz. What is the time between successive wave crests? Period = 1/ Frequency Period = 1 / 262 Hz Period = .0038s 2. A sound wave produced by a clock chime 515 m   away is heard 1.50   s   later. The frequency of the sound is 436 Hz. (a) What is the speed of sound in air? (b) What is the period of the sound wave? (c) What is its wavelength?

(a) Velocity = delta distance / delta time Velocity = 515m / 1.50s = 343.3 m/s

(b) Period = 1 / Frequency Period = 1 / 436 Hz Period = .00229s

(c) Velocity = Wavelength * Frequency Velocity / Frequency = Wavelength 343.3 m/s / 436 Hz = .7874 m

[] Suppose that the two speakers in the figure are separated by 2.50 m and are vibrating exactly //out of phase// at a frequency of 429 Hz. The speed of sound is 343 m/s. Does the observer at C observe constructive or destructive interfernce when his distance from speaker B is

Δd=(n+1/2)λ > > > >
 * 1) The Δd would can be find by finding the difference between the AC and BC.
 * 2) BC and AB are given and it can be seen in the pictuce that angle ABC is 90 degrees.
 * 3) AC can be found using the pythagorean theorem.
 * 4) AB^2 + BC^2 = AC^2
 * 5) AC = 4
 * 6) Δd = 4m - 2.4m = 1.6m
 * 7) Now we need to find the wavelength
 * 8) Velocity = Wavelength * Frequency
 * 9) Wavelength = Velocity / Frequency = .800m
 * 10) (Δd/λ) - .5 will determine whether or not the there is constructive or destructive interference.
 * 11) (16m/.800m) - .5 = 1.5 There is destructive interference.

Website with good description and animation of constructive and dustructive interference

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 * __Interesting Videos, pictures, and links__**



Image of the Acoustic Mirror
 * __SOURCES__**
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