Flashcards in ch 7 - Waves and Sound Deck (58)

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1

## sinusoidal waves

### waves that may be transverse or longitudinal in which the individual particles oscillate back and forth with a displacement that follows a sinusoidal pattern.

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## transverse waves

### those waves in which the direction of the particle oscillation is perpendicular to the propagation (movement) of the wave; ex are electromagnetic waves such as visible light, microwaves and x-rays

3

## longitudinal waves

### waves in which particles of wave oscillate parallel to the direction of propagation, oscillating in direction of energy transfer; ex sound waves

4

## distance from one maximum (crest) of a wave to the next

### wavelength represented by the upside down y

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## number of wavelengths passing a fixed point per second

### frequency (f), measured in hertz (Hz) or cycles per second

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## propagation speed (v) of a wave

### v = f x upside down y (propagation speed = frequency x wavelength

7

## period equation (inverse of frequency)

### T = 1/f. Period = 1/f, defines the number of seconds per cycle

8

## angular frequency

### fancy w = 2pi x f = (2pi)/T measured in radians per second

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## equilibrium position

### central point around which waves oscillate

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## displacement (x)

### in waves, describes how far a particular point on the wave is from the equilibrium position, vector quantity

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## amplitude (A)

### maximum magnitude of displacement from the equilibrium position to the top of the crest or bottom of a trough, in a wave

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## phase difference

### measure of how "in step" or "out of step" waves are. If in same place at same time with same amplitude, frequency and wavelength then phase difference = 0

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## principle of superposition

### states that when waves interact with each other, the displacement of the resultant wave at any point is the sum of the displacements of the two interacting waves

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## constructive interference

### in principle of superposition, when waves are perfectly in phase, the displacements are always the sum of the amplitudes of the two waves

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## destructive interference

### in principle of superposition, when waves are perfectly out of phase, then the displacements are always the difference between the amplitudes of the two waves

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## travelling wave

### moving wave from moving end of string or source to immobile end; if end is continuously moving waves will come back and still be going out and interfere with each other

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## standing waves

### fluctuation of amplitude along fixed points along length of string or whatever waves are on;

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## nodes

### points on something producing standing waves that remain at rest (where amplitude is constantly zero)

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## antinodes

### points on something producing standing waves midway between the nodes that fluctuate with maximum amplitude

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## natural (resonant) frequencies

### sounds that naturally come from certain objects

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## timbre

### quality of sound; determined by the natural frequencies of an object

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## noise

### scientifically it is produced by objects that vibrate at multiple frequencies that have no relation to one another

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## frequency range generally audible to health young adults

### 20 Hz to 20,000 Hz

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## forced oscillation

### if a periodically varying force is applied to a system, the system will then be driven at a frequency equal to the frequency of the force

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## resonating system

### occurs when the frequency of the periodic force is equal to a natural (resonant) frequency of the system; amplitude of the oscillation is at a max

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## damping (attenuation)

### a decrease in amplitude of wave caused by an applied or nonconservative force

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## equation for speed of sound

### v = square root of (B/fancy p) where B is bulk modulus, a measure of medium's resistance to compression (B increases from gas to liquid to solid), fancy p = density of the medium; fastest in a solid with low density and slowest in a gas with high density

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## approximate speed of sound in air

### 343 m/s

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## pitch

### our perception of the frequency of sound

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