science waves and sound Flashcards
the ability to do work
energy
a disturbance that transfers energy from place to place
wave
the material through which a wave travels
medium
What is the medium for sound waves?
air
What is the material through which water waves travel?
along the water surface
Waves that travel through a medium are what kind of waves? Does the medium move with the mechanical wave?
mechanical waves - no
Give an example of an electromagnetic wave that can travel through empty space.
light
What type of wave can travel without a medium?
electromagnetic waves - light
Why doesn’t the medium travel with the wave?
The wave transfers the energy to the medium’s particles.
What is necessary to cause a wave?
energy causes a medium to vibrate
What is vibration?
a repeated back and forth or up and down motion
What are the two types of mechanical waves, and how are they classified?
transverse waves - - moves at right angles to the direction the wave is traveling
longitudinal waves - move parallel to direction wave is traveling
What is the high point on a transverse wave?
crest
What is the low point on a transverse wave?
trough
What do we call the coils in a longitudinal wave that are closer together?
compressions
What do we call the coils in a longitudinal wave that are further apart?
rarefactions
Is sound a longitudinal or a transverse wave?
longitudinal
What is amplitude of a transverse wave?
the height of the crest or the depth of a trough
What is the amplitude of a longitudinal wave?
the density of the compression or how spread out the rarefaction
What increases the amplitude of a wave?
energy
What is the distance between two corresponding parts of a wave?
crest to crest or trough to trough or distance between compressions
wavelength
the number of waves that pass a given point in a certain amount of time
frequency
What unit is frequency measured in?
hertz (Hz), waves per second
What is the relationship between speed, wavelength, and frequency
speed = wavelength X frequency
What happens to the speed of a wave at a constant temperature and pressure if the medium doesn’t change?
speed is constant
when an object or a wave hits a surface through which it cannot pass it bounces back and is called what
reflection
Give 2 examples of reflections.
ball bouncing off a wall
echo of sound
What is the law of reflection?
angle of incidence equals the angle of reflection
Where is the line of “normal?”
perpendicular
What is the angle of incidence?
from the incoming wave to “normal”
What is the angle of reflection?
from “normal” to the reflected wave
What is refraction?
bending
What causes waves to refract or bend?
when a wave enters a new medium at an angle and one side changes speed before the other side
How is a rainbow an example of refraction?
The white light hits the water droplets and bends.
What is it called when a wave moves around a barrier or through an opening in a barrier, it bends and spreads out?
diffraction
the interaction of waves that meet
interference
What are the two types of interference?
constructive - waves combine for a larger amplitude
destructive - waves combine for a smaller amplitude
What is the new amplitude when two constructive waves meet?
sum of original amplitudes
What is the new amplitude when two destructive waves meet?
difference between original amplitudes
a wave that appears to be standing in one place, actually two waves interfering as they pass through each other
standing wave
What are the points of zero amplitude on a standing wave?
nodes
What are the points of maximum amplitude on a standing wave?
antinodes
What spots are the points of maximum energy on a standing wave?
antinodes
an increase in the amplitude of a vibration that occurs when external vibrations match an object’s natural frequency
resonance
When can resonance be good?
a musical instrument can make a fuller sound
When can resonance be bad?
in an earthquake when the resonance causes more damage
waves produced by earthquakes
seismic
Name, and describe the three types of seismic waves.
P - primary - move faster - arrive first, made of compressions and rarefactions of molten rock
S - secondary - transverse, shake ground up and down and side to side, don’t travel through liquids
surface waves - combination waves on surface, move most slowly, make ground roll
Why can’t S waves be seen on the other side of the Earth?
core is molten
surface waves on the ocean
tsunamis
What makes tsunamis so large?
Waves further back catch up as water gets more shallow
tool for measuring seismic activity
seismograph - compare P and S waves and using at least three seismographs
How do scientists use seismographs to find oil and other resources?
set off explosives and measure waves
What do sound waves begin with?
vibration
What type of wave is sound?
longitudinal wave
What is a reflected sound wave?
echo
What factors affect the speed of sound?
elasticity, density, and temperature of the medium
ability of a material to bounce back after being disturbed
elasticity
Why does sound travel better in solids than in liquids or gases?
more elastic
how much matter or mass is in a given volume
density
The more dense a material of the same state, the (faster or slower) sound travels.
slower
What does temperature do to the speed of sound? Why?
travels more slowly at lower temperatures because particles are moving more slowly
Who was the first person to break the sound barrier? How did he do it?
Captain Chuck Yeager - went to a higher altitude where sound travels more slowly
your perception of the energy of a sound
loudness
What two factors affect loudness?
energy it takes to make the sound (amplitude) and distance from the source of the sound
the amount of energy a sound wave carries per second through a unit area - why does this decrease with distance
intensity - sound waves spread out
the unit used to measure the loudness of a sound
decibels (dB)
the frequency of a sound wave
pitch - high or low sounds
Within what decibel range can most people hear?
20-20,000Hz
What do we call frequencies above and below our range of hearing?
ultrasonic - above
infrasonic - below
your voice box
larynx
What vibrates inside your voice box?
vocal cords
What happens to the vocal cords to change the pitch of a sound?
tighten or relax
the phenomenon where a moving sound causes the frequency to change
Doppler Effect
the loud noise when a plane breaks the sound barrier and sound waves overlap
sonic boom
a set of notes in a pleasing pattern
music
the lowest natural frequency of an object
fundamental tone
the objects higher natural frequencies beyond its fundamental tone
overtones
What determines the loudness of the overtones in a musical instrument?
shape and material
What are the three basic groups of musical instruments?
string - strings vibrate
wind - brass (lips vibrate on mouthpiece) and woodwind (reed vibrates) to move a column of air - longer columns make a lower note
percussion - vibrate when struck - pitch depends on size, material, and tension
the study of how sounds interact with one another and the environment
acoustics
when the echoes of a sound are heard after the sound source stops
reverberation
How are acoustics used in the design of concert halls?
to control reverberation and interference
What does the outer ear do to sound?
funnels it
the tube from the outer ear to the eardrum
ear canal
the stretched membrane at the end of the ear canal
eardrum
What makes up the middle ear?
three bones - hammer, anvil, and stirrup
the fluid-filled snail-shaped chamber in the inner ear
cochlea
What structures in the cochlea of the inner ear move to hear?
hair cells
What can cause hearing loss?
injury, infection, aging, and exposure to loud sounds
What is the most common kind of hearing loss as hair cells die and are not replaced
loss of high frequency sounds
some animals, including bats and dolphins
echolocation
Bats and dolphins use what type of sound for echolocation?
ultrasonic
How do dolphins sense the reflected sound waves?
their jaw bones
How do bats sense reflected sound waves?
their ears
a system employed by humans to use reflected sound waves to locate objects underwater
sonar - sound navigation and ranging
What is sonar used for?
mapping ocean floor, finding sunken ships, determining depth
How does sonar work?
the longer it takes sound to bounce back, the farther away the object
sound imaging techniques in the body
sonogram, ultrasound
