Intro to Waves Flashcards
When an object repeats a pattern of
motion, we say that it exhibits _______ ______.
periodic motion
periodic motion
occurs when a movement repeats itself in regular time intervals.
The repeated pattern is called a _____
cycle
Objects that exhibit periodic motion
usually are ________ or ________.
vibrating; oscillating
A vibration is a cyclical motion around
some ___________ _______.
equilibrium point
transverse vibrations
Motion is at a 90° to its length
longitudinal vibrations
Motion is parallel to its length
torsional vibrations
Object twists around its axis at the rest position
The ________ is the maximum distance
from the rest or equilibrium position
Amplitude
The _________ is the time needed to
complete 1 cycle.
Period (T)
Frequency (f)
the number of cycles that occur in a unit of time
Two identical pendulums are said to be
vibrating __ _____ if they have the same
period and pass through the rest position
at the same time.
in phase
They are vibrating ___ __ ______ if they do not have the same period or if they have the same period but they do not pass through the rest position at the same time.
out of phase
A _________ _____ is a disturbance
that transfers energy through a ________
(solid, liquid, or gas) by means of a
series of vibrations.
mechanical wave; medium
All vibrations require a _______ in order
to transfer a ______.
medium; wave
When vibrating, the medium itself does not ____ __ ____ energy.
gain or lose
_______ is transmitted by the wave, but
the whole medium does not move.
Energy
______ waves are waves where the
motions are repeated at regular time intervals.
Periodic
However, a periodic wave can also
consist of a single disturbance called a
______-, or shock wave.
pulse
A ___________ is the distance between
two points on a wave that are vibrating in
phase with each other.
wavelength
how do you find the wavelength
It is easiest to
calculate by finding the distance from the
midpoint of one crest to the midpoint of
the next crest (or from the midpoint of
one trough to the midpoint of the next).
A wavelength is represented by the …
Greek letter λ (lambda).
A ________ wave is one in which the
medium (like air or water) vibrates at a
right angle (90º) to the direction of the
flow of energy.
transverse
Each of the points along the wave is
vibrating __ ____ _____, but not moving
along the x-axis at all.
up and down
The wave has some parts above the
equilibrium position called _____ and
some parts below the equilibrium
position called _______.
crests; troughs
In _________ waves, the lengths of
successive crests and troughs are ______-.
periodic; equal
In a _________ wave, the particles of
the medium vibrate back and forth
parallel to the direction of the flow of
energy.
longitudinal
Points at which the particles are closer
together than normal are called
__________.
compressions
Parts where particles
are farther apart than normal are called
___________.
rarefactions
A ________ in a longitudinal wave is
the distance between two rarefactions or
two compressions.
wavelength
Sound Waves – _________
longitudinal
Sound Waves – longitudinal. The
molecules (usually air) are displaced
back and forth in the direction of the
_____ __________.
wave motion
Water waves – _____ ___________ .
mostly transverse
Water waves – mostly transverse. But
some longitudinal also. Your textbook
calls these “complex waves” because
they have both _________.
properties
explain the difference between a wave and a vibration
A vibration is the cyclical motion of an object
about an equilibrium point.
A wave is the transfer of energy through a material due to vibration.
Vibration is the cause and the wave is the effect
What properties of a medium allow a wave to pass through most effectively? Provide an example
The density of the medium allows a wave to pass
through most effectively.
For example, a tuning fork is a solid with high density, so it sustains vibrations for longer time as waves pass through it more effectively
Figure 6 is an image of an electric ringer inside a bell jar.
A vacuum pump can be connected to the jar. You turn the ringer on, and slowly start removing the air from the bell jar. Then you slowly allow the air back in.
(a) Predict how the sound from the ringer will change as you remove the air and then as you allow the air back in.
Sound reduces as the air is removed from the
jar and increases as the air is pumped back into the
jar.
Figure 6 is an image of an electric ringer inside a bell jar.
A vacuum pump can be connected to the jar. You turn the ringer on, and slowly start removing the air from the bell jar. Then you slowly allow the air back in.
(b) Explain why the sound will change.
Sound waves require a medium to move
through. As the air is removed from the jar, the
density of the medium decreases so the sound
decreases.
Contrast wavelength and amplitude for longitudinal waves
In longitudinal waves, amplitude is the maximum pressure created and the same definition of wavelength applies.
Contrast wavelength and amplitude for transverse waves
In transverse waves, wavelength is the distance
between two similar points in successive identical
cycles in a wave.
In transverse waves, amplitude is the maximum displacement of a vibrating particle in a wave.
