
Distinguish local particle vibrations from overall
wave motion.

Differentiate between pulse waves and
periodic waves.

Interpret waveforms of transverse and
longitudinal waves.

Apply the relationship among wave speed,
frequency, and wavelength to solve problems.

Relate energy and amplitude.

Waves are everywhere. Whether we recognize it or
not, we encounter waves on a daily basis. Sound
waves, visible light waves, radio waves, microwaves,
water waves, sine waves, cosine waves, stadium
waves, earthquake waves, waves on a string, and
slinky waves and are just a few of the examples of our
daily encounters with waves. In addition to waves,
there are a variety of phenomena in our physical
world that resemble waves so closely that we can
describe such phenomenon as being wavelike. The
motion of a pendulum, the motion of a mass
suspended by a spring, the motion of a child on a
swing, and the "Hello, Good Morning!" wave of the
hand can be thought of as wavelike phenomena.
Waves (and wavelike phenomena) are everywhere!
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So waves are everywhere. But what makes a wave a
wave? What characteristics, properties, or behaviors
are shared by the phenomena that we typically
characterize as being a wave? How can waves be
described in a manner that allows us to understand
their basic nature and qualities?
A wave can be described as a disturbance that
travels through a medium from one location to
another location. Consider a slinky wave as an
example of a wave. When the slinky is stretched from
end to end and is held at rest, it assumes a natural
position known as the equilibrium or rest position.
A wave is the motion of a disturbance.

But what is meant by the word medium? A medium is a
substance or material that carries the wave. You have
perhaps heard of the phrase news media. The news
media refers to the various institutions (newspaper offices,
television stations, radio stations, etc.) within our society
that carry the news from one location to another. The
news moves through the media. The media doesn't make
the news and the media isn't the same as the news. The
news media is merely the thing that carries the news from
its source to various locations. In a similar manner, a wave
medium is the substance that carries a wave (or
disturbance) from one location to another. The wave
medium is not the wave and it doesn't make the wave; it
merely carries or transports the wave from its source to
other locations.

Waves that require a medium through
which to travel are called mechanical
waves. Water waves and sound waves
are mechanical waves.

Electromagnetic waves such as visible
light do not require a medium.

Waves come in many shapes and forms.
While all waves share some basic
characteristic properties and behaviors,
some waves can be distinguished from
others based on some observable (and
some non-observable) characteristics. It
is common to categorize waves based
on these distinguishing characteristics.

A wave that consists of a single traveling pulse
is called a pulse wave.

Whenever the source of a wave’s motion is a
periodic motion, such as the motion of your
hand moving up and down repeatedly, a
periodic wave is produced.

A wave whose source vibrates with simple
harmonic motion is called a sine wave. Thus, a
sine wave is a special case of a periodic wave
in which the periodic motion is simple
harmonic.

A transverse wave is a wave in which particles of the
medium move in a direction perpendicular to the
direction that the wave moves. Suppose that a slinky
is stretched out in a horizontal direction across the
classroom and that a pulse is introduced into the
slinky on the left end by vibrating the first coil up and
down. Energy will begin to be transported through
the slinky from left to right. As the energy is
transported from left to right, the individual coils of
the medium will be displaced upwards and
downwards. In this case, the particles of the medium
move perpendicular to the direction that the pulse
moves. This type of wave is a transverse wave.
Transverse waves are always characterized by
particle motion being perpendicular to wave motion.
ove
longitudinal wave is a wave in which
particles of the medium move in a
direction parallel to the direction that
the wave moves. Suppose that a slinky
is stretched out in a horizontal direction
across the classroom and that a pulse
is introduced into the slinky on the left
end by vibrating the first coil left and
right. Energy will begin to be
transported through the slinky from left
to right. As the energy is transported
from left to right, the individual coils of
the medium will be displaced leftwards
and rightwards. In this case, the
particles of the medium move parallel
to the direction that the pulse moves.
This type of wave is a longitudinal
wave. Longitudinal waves are always
characterized by particle motion being
parallel to wave motion.
Crest: is the highest point above the
equilibrium position
 Trough: Is the lowest point below the
equilibrium position
 Wavelength: Is the distance between
two adjacent similar points of a wave,
such as from crest to crest or from trough
to trough


The frequency of a wave describes the
number of waves that pass a given point in
a unit of time.

The period of a wave describes the time it
takes for a complete wavelength to pass a
given point.

The relationship between period and
frequency in SHM holds true for waves as
well; the period of a wave is inversely
related to its frequency.

The speed of a mechanical wave is
constant for any given medium.

The speed of a wave is given by the
following equation:
v = f
wave speed = frequency  wavelength

This equation applies to both mechanical
and electromagnetic waves.

A piano string tuned to middle c vibrates
with a frequency of 262 Hz. Assuming the
speed of sound in air is 343 m/s, find the
wavelength of the sound wave produce
by the string.
ruby-throated hummingbird beats its
wings at a rate of about 70 wing beats
per second.
 a. What is the frequency in Hertz of the
sound wave?
 b. Assuming the sound wave moves with
a velocity of 350 m/s, what is the
wavelength of the wave?

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
Waves transfer energy by the vibration of
matter.
Waves are often able to transport energy
efficiently.
The rate at which a wave transfers energy
depends on the amplitude.
› The greater the amplitude, the more energy a wave
carries in a given time interval.
› For a mechanical wave, the energy transferred is
proportional to the square of the wave’s amplitude.

The amplitude of a wave gradually diminishes
over time as its energy is dissipated.

Do problems 1-3 in your book page 383
Today we learned about the properties
of waves
 Next class we are going to have a lab
