Chapter 1
Lesson 1 - "What Are Waves?"
What Are Waves?
What Are Mechanical Waves? -- most of us think of waves of water but there are
other types of waves that affect us daily.
Characteristics of Waves
Definition: a disturbance involving the transfer of energy from place to place.
*Remember that energy is defined as the ability to do ___work_______.
*Most waves need something to travel through, we call that material a medium
.
What are some mediums for waves?
1. Liquid
2. Solid
3. Gases
*If a wave requires a medium to travel we call them ___mechanical______ waves.
Waves and Energy
*Mechanical waves form when a source of energy causes a medium to vibrate.
Definition: a repeated back-and-forth or up-and-down motion is a vibration.
Energy Source
*moving objects have energy
Vibration
*when a vibration moves
through a medium, a wave
results
Medium
*mechanical waves form in mediums
What Are The Types of Waves?
Waves move through mediums in different ways. They are classified by how they
move through mediums
There are 3 different types of mechanical waves:
1. Transverse - a wave that vibrates the medium at right angles, or perpendicular, to
the direction in which the wave travels.
*When a transverse wave is created the high and low points are given names:
crest = high point
trough = low point
2. Longitudinal - vibrates the medium in the same direction the wave travels.
*When longitudinal waves vibrate they create two spacing situations:
compression = coils are close together
rarefaction = coils are spread out
What Are The Types of Waves?
3. Surface Waves - a combination of transverse and longitudinal waves.
**This type of wave travels along a surface that separates two mediums.
Chapter 1
Lesson 2 - "Properties of Waves"
What Are the Amplitude, Wavelength, Frequency, and Speed of a Wave?
Waves can vary greatly. Some are long or short. They can carry a lot or a little
energy. What they all have in common is that they possess these properties:
Properties of Waves:
Amplitude - the maximum distance the medium vibrates from the rest position.
*For water waves this is the distance the water particles move above or below the
surface level of calm water.
*The more energy a wave has the greater its amplitude.
Transverse = max. distance medium moves up or down from rest
Longitudinal = how compressed or rarefied medium becomes
*Draw in your notes a wave
with an amplitude of 2.5cm.
What Are the Amplitude, Wavelength, Frequency, and Speed of a Wave?
Waves can vary greatly. Some are long or short. They can carry a lot or a little
energy. What they all have in common is that they possess these properties:
Properties of Waves:
Amplitude - the maximum distance the medium vibrates from the rest position.
*For water waves this is the distance the water particles move above or below the
surface level of calm water.
*The more energy a wave has the greater its amplitude.
Transverse = max. distance medium moves up or down from rest
Longitudinal = how compressed or rarefied medium becomes
*Draw in your notes a wave
with an amplitude of 2.5cm.
What Are the Amplitude, Wavelength, Frequency, and Speed of a Wave?
Wavelength - the distance between two corresponding parts of a wave.
Transverse = measure distance from crest to crest.
Longitudinal = the distance between compressions.
*Draw in your notes a wave
with an wavelength of 2.5cm.
What Are the Amplitude, Wavelength, Frequency, and Speed of a Wave?
Frequency - the number of waves that pass a given point in a certain
amount of time.
*Measured in units called hertz(Hz). Hertz = number of waves/s.
*What is the frequency of the
tone that you are hearing?
What Are the Amplitude, Wavelength, Frequency, and Speed of a Wave?
Speed - how far the wave travels in a given amount of time.
*Light waves travel about a million times faster than sound waves.
*To determine the speed do the following:
Distance Traveled
Time Traveled
*Sound travels about 990m in 3 seconds.
*What is the speed of sound?
What Are the Amplitude, Wavelength, Frequency, and Speed of a Wave?
Speed - how far the wave travels in a given amount of time.
*Light waves travel about a million time faster than sound waves.
*To determine the speed do the following:
Distance Traveled
Time Traveled
*Sound travels about 990m in 3 seconds.
*What is the speed of sound?
How Are Frequency, Wavelength and Speed Related?
Speed = wavelength x Frequency
Frequency =
Wavelength =
*The speed of a wave remains constant if the medium, temp., and
pressure do not change. i.e. All sound waves travel at the same
speed in air at a given temp. and pressure.
*Complete the
chart in your
notebook.
If the _________ increases of a soundwave, its ___________must decrease to
maintain a constant speed.
11.The lowest pitch that the average human can hear has a
frequency of 20.0 Hz. If sound with this
frequency travels through air with a speed of 331 m/s, what
is its wavelength?
12.A ship anchored at sea is rocked by waves that have
crests 14 m apart. The waves travel at 7.0 m/s. How
often do the wave crests reach the ship?