Chapter 25 Flashcards
Who discovered that the time a pendulum takes to swing back and forth through small angles depends only on the length of the pendulum—the mass has no effect?
Galileo
Period
The time of a back-and-forth swing of the pendulum
What does the period of the pendulum depend on?
Only on the length of a pendulum and the acceleration of gravity
4). Does a long pendulum have a longer period or does a shorter pedulum have a longer period.
long pendulum
5). Why does a long pendulum have a longer period?
it swings back and forth more slowly—less frequently—than a short pendulum
What is the back-and-forth vibratory motion (often called oscillatory motion) of a swinging pendulum called?
simple harmonic motion
What is a sine curve?
a pictorial representation of a wave
What is the source of all waves?
something that vibrates
crests
the high points on a wave
The low points on a wave are called..
troughs
What does the term amplitude refer to?
the distance from the midpoint to the crest (or trough) of the wave
What does the amplitude equal?
the maximum displacement from equilibrium
What is the wavelength of a wave?
the distance from the top of one crest to the top of the next one/the distance between successive identical parts of the wave
What are the wavelength at the beach measured in?
meters
What are the wavelengths in the pond measured in?
centimeters
What is an object’s frquency>
The number of vibrations an object makes in a unit of time
A complete back-and-forth vibration is…
one cycle
The frequency of the vibrating source and the frequency of the wave it produces are the same. T OR F
True
The unit of frequency is called the…
hertz (Hz)
A frequency of one cycle per second is _______, two cycles per second is _______.
1Hz; 2Hz
Higher frequencies are measured in…
Kilohertz and/or Megahertz
Formula for frequency and period
frequency = 1/period; period = 1/frequency
How does most of the information around us get to us?
In some form of wave
Sound is energy that…
travels to our ears in the form of a wave
Light is energy that…
comes to our eyes in the form of a different kind of wave (an electromagnetic wave)
When energy is transferred by a wave from a ___________source to a distant __________, there is no _________of matter between the two points.
vibrating; receiver; transfer
When an end of the string is shaken, a rhythmic disturbance travels along the string, the _________that moves along the length of the string.
disturbance
When a stone is dropped in a quiet pondm the disturbance moves and the water doesn’t and the disturbance passes, where does the water end up?
right where it was before the wave passes
When someone speaks to you from across the room, the disturbance in the air that travels across the room. Do the air molecules move?
No, they are the medium through which wave energy travels.
The energy __________by a _____from a ___________source to a ________is carried by a __________in a ___________.
transferred; wave; vibrating; disturbance; receiver; mediu,
What does the speed of a wave depend on?
the medium through which the wave
moves
Are the speed, wavelength, and frequency, no matter the medium, aslways related?
Yes
You can calculate the speed of multiplying the…
wavelength by the frequency
Long wavelengths have ______frequencies and short wavelengths have _________frequencies.
low; high
Wavelength and frequency vary ________to produce the same wave speed for all sound.
inversely
Transverse wave
Whenever the motion of the medium is at right angles to the direction in which
a wave travels
Waves in the stretched strings of musical instruments and the _____________aves that make up radio eaves and light are transverse.
electromagnetic
Are all waves transverse?
No
Sometimes the particles of the ________move back and forth in the ________direction in which the wave travels.
medium; same
Longitudinal wave
When the particles oscillate parallel to or along the direction of the wave rather than at right angles to it
What waves are longitudinal waves
sound waves
How are transverse waves demonstrated in a slinky?
By shaking it up and down
How are longitudinal waves demonstrated in a slinky?
By shaking the end in and out.
Interference pattern
A regular arrangement of places where wave effects are increased, decreased, or neutralized.
When do interfernce patterns occur?
When waves from different dources arrive at the same - at the same time
Constructive Interference
the crest of one wave overlaps the crest of another and their individual effects add together
What is the result of constructive interference?
A wave of increased amplitude (reinforcement)
Destructive Interference
the crest of one wave overlaps the trough of another and their individual effects are reduced (cancellation)
Where wave interference easiest to see?
In water
What happens along the regions where waves cancel each other out>
The two objects arrive “out of step”/”out of phase”
What happens when waves are “out of phase”
the crests of one wave overlap the troughs of another to produce regions of zero amplitude
What happens when waves are “in phase”
the crests of one wave overlap the crests of the other, and the troughs overlap as well
What is the moiré pattern is formed similar to?
the interference pattern of waves
Is interference a characteristic of all wave motions?
Yes
Standing wave
a wave that appears to stay in one place—it does not seem to move through the medium
What are nodes?
the stationary points on a standing wave
What are antinodes?
The positions on a standing wave with the largest amplitudes
Where do antinodes occur?
halfways between nodes
Standing waves are the result of interference. T or F
True
When two waves of equal amplitude and wavelength pass through each other in opposite directions, the waves are…
always out of phase at the nodes
How can you produce a variety of standing waves?
By shaking the rope at different frequencies
A standing wave forms only if ________a wavelength or a __________of _______a wavelength fits exactly into the length of the _____________ __________.
half; multiple; half; vibrating medium
If you increase the frequency, you…
increase the amount of interesting waves
Can standing waves be produced in either transverse or longitudinal waves?
Yes
Situation: bug is treading in water in a fixed position.
what type of circle does the crests of its wave make?
concentric
If the bug bobs in the water at a constant frequency, the distance between wave crests (wavelength) will be what for all successive waves? Is the frequency the same as well?
the same; the same
What happens when the jiggling bug moves across the water at a speed less than the wave speed?
The bug chases part of the crests it has produced, the wave pattern is distorted and is no longer concentric.
As a wave source approaches, an observer encounters waves with a ________frequency . As the wave source moves away, an observer encounters waves with a ________frequency
higher; lower
Doppler effect
This apparent change in frequency due to the motion of the source (or receiver)
Water waves spread over the ____________surface of the water
flat
Sound and light waves, on the other hand, travel in ______________.
three-dimensional space in all directions like an expanding balloon.
When the firetruck approaches, the pitch sounds higher than normal. Why?
This occurs because the sound wave crests are encountering you more frequently
An increase in frequency in light is called…
a blue shift, bc the increase is toward the high-frequency, or blue, end of the color spectrum
A decrease in frequency in light is called…
a red shift, bc the increase is toward the low-frequency, or red, end of the color spectrum
A bow wave occurs when…
a wave source moves faster than the wave it produces.
What is the shape of the bow wave
A v shape
What is a shock wave?
a three-dimensional wave that consists of overlapping spheres that form a cone
When does a shock wave occur?
When an object moves faster than the speed of sound
When do we hear a sonic boom on an aircraft?
Only when the craft moves faster than sound do the crests overlap and encounter the listener in a single burst
