Ch 17 PS

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A disturbance in matter that carries energy from one place to another.: Mechanical wave
The ability to do work: Energy
Mechanical waves require _____ to travel through: matter
Material through which a wave travels: medium
3 mediums are...: solids, liquids, and gasses
In a wave pool, what is the medium?: Water
Waves travel through a rope when you shake one end of it. What is the medium?: The rope
When is a mechanical wave created?: When a source of energy causes a vibration to travel through a medium.
Mechanical waves are classified...: by the way they move through a medium
3 types of mechanical waves: transverse, longitudinal, and surface
The highest point of a (transverse) wave above the rest position: crest
the lowest point below the rest position (transverse): trough
A transverse wave carries energy in a direction ________ to the up and down motion of the medium.: perpendicular
an area where the particles in a medium are spaced close together (longitudinal): compression
area where the particles in a medium are spread out (longitudinal): rarefaction
a wave in which the vibration of the medium is parallel to the direction the wave travels: longitudinal
Longitudinal waves produced by earthquakes that can travel through earth- scientist use them to map earth's unseen interior.: P waves (aka primary waves)
Most familiar kind of surface wave: Ocean waves
A wave that travels along a surface seperating two media: surface wave
any motion that repeats at regular time intervals: periodic motion
A complete motion that returns to its starting pt (the time required for one cycle): period
For an ocean wave, the period is the time between...: two successive crests
# of complete cycles in a given time: frequency
For a wave, the _____ is the number of wave cycles that pass a point in a given time: frequency
Frequency is measured in..: cycles per second, or hertz (Hz)
A wave's frequency equals..: the frequency of the vibrating source producing the wave
the dist. betwn a point on one wave and the same point on the next cycle of the wave: Wavelength
For a transverse wave, wavelength is: measured between adjacent crests or adjacent troughs
For a longitudinal wave, wavelength is: the distance btwn adjacent compressions or rarefactions.
Increasing freqency of a wave _____ its wavelength.: decreases
Speed =: wavelength x frequency
The speed of a wave can change if: it enters a new medium, or if variables such as pressure and temperature change
If you assume that waves are traveling at a constant speed, then..: wavelength is inversely proportional to frequency.
A wave with lower frequency has ____ wavelength.: longer
Max displacement of the medium from its rest position: Amplitude
The amplitude of a transverse wave is...: the distance from the rest position to a crest or a trough
It takes more energy to produce a wave with..: higher crests and deeper troughs
The more energy a wave has, the ______ its amplitude: greater
To measure the amplitude of a longitudinal wave...: use the max displacement of a point from its rest position (the more energy the wave has, the more the medium will be compressed or displaced)
occurs when a wave bounces off a surface that it cannot pass through: reflection
Reflection does not change the ___ or ___ of a wave but the wave can be flipped upside down.: speed, frequency
The reflected wave will be upside down compared to the original wave if the reflection occurs at...: a fixed boundary
the bending of a wave as it enters a new medium at an angle: Refraction
When a wave enters a medium at an angle, refraction occurs because..: one side of the wave moves more slowly than the other side
the bending of a wave as it moves around an obstacle or passes through a narrow opening.: Diffraction
When waves bend around an obstacle, _____ can also occur.: Diffraction
A wave diffracts more if its wavelength is...: large compared to the size of an opening or obstacle
When diffraction occurs, if the wavelength is small compared to the opening or obstacle, the wave..: bends very little
When diffraction occurs, the larger the wavelength is compared to the size to the opening or obstacle, the wave: diffracts more.
occurs when two or more waves overlap and combine together: interference
Two types of intereference: Constructive, destructive
The displacements of a wave combine to...: increase amplitude in constructive destructive interferenceintereference and decrease amplitude in destructive interference
Occurs when two or more waves combine to produce a wave with a larger displacement: Constructive interQference
Can reduce the amplitude of a wave: destructive interference
Occurs when two or more waves combine to produce a wave with a smaller displacement: Destructive interference
When a crest meets a crest, the amplitude...: increases
When a crest meets a trough, the amplitude...: is reduced
A wave that appears to stay in one place and does not seem to move through the medium: standing wave
Point on a standing wave that has no displacement from the rest position: Node
A point where a crest or trough occurs midway between two nodes: antinode
A standing wave forms only if half a wavelength or a multiple of half a wavelength...: fits exactly into the length of a vibrating cord
Longitudinal waves- compressions and rarefactions- that travel through a medium.: Sound waves
Many behaviors of sounds can be explained using.. (5): speed, intensity, loudness, frequency, and pitch.
Waves travel fastest in ___ slower in ____ and slowest in ____: solids, liquids, gasses
(particles in a solid are closer together than particles in a liquid or gas)
The speed of sound depends on...: density and elasticity of the medium
the rate at which a wave's energy flows through a given area: Intensity
Sound intensity depends on both...: the wave's amplitude and the distance from the sound source
Sound intenisty levels are measured in...: decibels (dB) - a unit that compares the intensity of different sounds
The decibel scale is based on...: powers of ten
a physical response to the intensity of sound, modified by physical factors.: Loudness
As intensity increases, loudness _____: increases
the frequency of sound as you percieve it: pitch
sound at frequencies lower than most people can hear: Infrasound
sound at frequencies higher than most people can hear: Ultrasound
Ultrasound is used in...: sonar and ultrasound imaging
a technique for determining the distance to an object under water.: Sonar
S.O.N.A.R: sound navigation and ranging
Each ultrasound puplse: 1/8000 of a second
A change in sound frequency caused by motion of the sound sorce, listener, or both.: Doppler effect
Doppler effect was discovered by...: Austrian scientist Christian Doppler. (1803-1853)
As a source of sound approaches, an observer hears a ____ frequency. As it moves away, a _____ frequency is heard.: higher, lower
3 system ear consists of: Outer ear, middle ear, and the inner ear
gathers and focuses sound into the middle ear: the outer ear
recieves and amplifies vibrations: middle ear
uses nerve endings to sense vibrations and send signals to the brain: inner ear
sound wave strikes eardrum, (a tightly stretched membrane between outer and middle) - & the eardrum vibrates at the same frequency as the sound waves striking it.: Outer ear
Contains hammer, anvil, & stirrup. When eardrum vibrates, the hammer vibrates at the same frequency. The hammer strikes the anvil, which moves the stirrup back and forth. The three bones act as a lever system to amplify the motion of the eardrum.: The middle ear
3 bones in middle ear: Hammer, anvil, & stirrup
Vibrations from the stirrup travel into the cochlea (a spiral shapes canal filled with fluid) The inside of the cochlea is lined w/ thousands of nerve cells with tiny hair-like projections. As the fluid in the cochlea vibrates, the projections sway back: Inner ear
Sound is recorded by...: converting sound waves into electronic signals that can be processed and stored.
Sound is reproduced by...: converting electronic signals back into sound wavesl
Most musical instruments vary their pitch by..: changing the frequency of standing waves
Musical instruments often use ___ to amplify sound: resonance
Response of a standing wave to another wave of the same frequency: Resonance
A wave entering a new medium at an angle will undergo _____ as one end of the wave changes speed.: Refraction
A cat can hear frequencies up to _______: 65,000 Hertz
The ______ is a line drawn perpendicular to the barrier in a reflective wave: normal
Instead of crests and troughs, as in an ocean wave, a longitudinal wave has _____ and ______: compassion & rarefaction
An _____ _____ is a frequency higher than most people can hear: ultrasonic soundwave
In a transverse wave, ______ is measured from crest to crest or from trough to trough: Doppler Effect
The crest of a transverse wave is most similar to a(an) ______ in a longitudinal wave: compression
A _____ is the material through which a mechanical wave travels: medium
_______ measures the greatest displacement of a wave from the rest position: amplitude
A wave in a rope is a transverse wave, but a sound in a wave is a _____ wave: longitudinal
At the _____ of a standing wave, there is no displacement from the rest position.: node
In 1970, ___ ____ worked with noise cancellation technology: Barry Chaplain
The standard measure used to compare sound intensities is the ______: decibel
Earthquake waves are ____ as they pass through different layers of earth: refracted
The range of human hearing is _____ to _____ Hz: 20 - 20,000 hertz
The _____ ____ is a change in sound frequency caused by motion of the sound source, motion of the listener, or both.: Doppler Effect
The part of the ear that is a funnel for sound waves is the _____ ear.: outer eat
____ ___ occurs when troughs of one waave meet crests of another wave.: interference
Once you find a frequency that produces a ____ ____, doubling or tripling the frequency will also produce it.: standing wave
Sounds greater than _____ dB can damage hearing.: 90 - 120 decibels
A line drawn showing the direction a wave travels on a reflective wave is called a _____: ray
If two waves collide and form a temporary larger wave, the interference is _____: constructive
An _____ ____ is a frequency lower than most people can hear.: infrasonic soundwave
Waves in a rope are transverse waves because the medium's vibration is ____ to the direction in which the wave travels.: at right angles
____ ____ breoke the sound barrier by flying at a speed of 293 m/s at an altitude of 12,0000 m.: Chuck Yeager

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