ch 17 2
Terms
undefined, object
copy deck
- studied noise cancellation
- percy chapman
- require matter to travel
- medium
- highest point on a wave
- crest
- lowest point on a wave
- trough
- causes medium to vibrate at right angles to the direction the wave travels
- transverse
- areas that are close together
- compression
- wave's energy moves left to right and is spread out
- rarefaction
- p waves
- primary waves
- wave that travels along a surface separating two media
- surface
- perpindicular to the direction in which the wave travels
- surface
- breaking crust vibrates creating SE, carry energy outward
- seismic waves
- forces in earth's crust can cause
- regions of the crust to shift bend or break
- combination of compressional and transerse waves
- travel through earth and along its surface
- objects on earth's surface absorb some energy from seismic waves....
- causing them to move and shake
- both seismic and transvese waves travel through a medium w/o
- transferring matter
- distance b/w a point on one wave and the same point on the next crest
- wavelength
- measured in m, km, cm
- wavelength
- maximum displacement of the medium from its resting position
- amplitude
- number of complete cycles in a given time
- frequency
- measured in hertz (Hz)
- frequency
- time required for one cycle to complete motion that returns to its starting point
- period
- 1/frequency
- period
- any motion that repeats at regular time intervals
- periodic motion
- a wave's frequency equals
- the frequency of the vibrating source producing the wave
- formula for wave speed
- v= wavelength times frequency
- increasing the frequency of a wave
- decreases its wavelength
- the more energy a wave has
- the greater its amplitude
- if you assume that waves are traveling at a constant speed then
- wavelengthis inversely proportional to frequency
- when a wave bounces off a surface that it cannot pass through
- reflection
- reflection does not change the speed or frequency of a wave but
- a wave can be flipped upside down
- how the wave is traveling
- ray
- line perpindicular to the barrier
- normal
- law of reflection
- angle of incidence is always equal to angle of reflection
- bending of a wave due to a chnage in its speed
- refraction
- refraction waves have the same frequency but
- different speeds/wavelengths
- when a wave enters a meduam at an angle
- refraction occurs b/c one side of the wave moves more slowly than the other side
- bending of a wave as it moves around an obstacle or passes through a narrow opening
- deffraction
- the amount of deffraction depends on
- wavelength and size of the obstacle
- two or more waves overlap nad combine together
- interference
- distance is added to the displacement of the other wave
- displacement
- combine to form a wave to form a larger displacement
- constructive interference
- forms only if half a wavelength (multiple)
- standing wave
- where the wave comes together on hte resting position
- node
- all of the crests and troughs
- antinode
- frequency of a standing wave can be multiplied
- to equal a standing wave
- compressions and rarefractions that travel through a medium
- longitudinal
- many behaviors of sound can be explained by using a few properties-
- speed, intensity and loudness, frequency and pitch
- sound waves travel fastest in
- solids
- sound waves travel slowest in
- gases
- depends on
- density of medium and elasticity
- rate at which a wave's energy flows through a given area
- intensity
- vibration that gives energy to the medium
- sound
- determined by temperature, elasticity& density of the medium
- speed of sound
- physical response to the intensity of sound, modified by physical factors
- loudness
- depends on the health of your ears and brain's interpretation of sound waves
- loudness
- depends on how fast the source of the sound vibrates
- frequency
- broke the sound barrier
- chuck yager
- wave's amplitude and distance from source
- intensity
- every 10 dB the intensity increase
- 10 folds
- if the sound intensity is greater than 120 dB.....
- it causes pain
- how high or low a note is
- pitch
- frequency is as how you perceive it, depends on health of your ears/ age
- pitch
- frequency is
- a characteristic of sound
- hertz our ears respond to
- 20 to 20000
- dogs Hz
- 35000
- cat Hz
- 65000
- porpoise Hz
- 150000
- higher frequencies than 20000Hz
- ultrasonic
- SONAR
- SOund NAvigation and Ranging
- below 20 Hz
- infrasonic
- change in sound frequency caused by the motion of sound source, motion of listener, or both
- doppler effect
- as a source of sound approaches
- an observer hearsa higher frequency
- when the sound source moves away
- the observer hears a lower frequency
- the outer ear.....
- focuses and gathers sound
- the middle ear.....
- receives and amplifies the vibrations
- inner ear
- uses nerve endings to sense vibrations and send signals to the brain
- ear canal where sound waves strike the eardrums
- outer ear
- a tightly strechted membrane b/w the outer and middle ear
- eardrum
- contains the hammer, anvil and stirrup. the eardrum vibrates and strikes the anvil which moves the stirrup back and forth
- middle ear
- contains the cochlea,the inside has nerves
- inner ear
- sound is recorded by
- converting sound waves into electronic waves into electronic signals that can be reproduced and stored
- sound is reproduced by
- converting electronic signals back to sound waves
- most musical instruments vary pitch by
- changing the frequency of standing waves
- the response of a standing wave to another wave of the same frequency
- resonance
- a wave entering a new medium at a right angle will undergo____as one end of the wace changes speed
- refraction
- a cat can hear frequencies up to
- 65,000 Hz
- The___is a line drawn perpindicular to the barrier in a reflective wave
- normal
- instead of crests and troughs, as in an ocean wave,a longitudinal wave has ___ and ___-
- compressions and rarefractions