Waves Jun8
Transcript of Waves Jun8
Happy Monday!June 8th 2015
Today’s Objectives:• Classify a Mechanical wave as Transverse,
Longitudinal, or Surface• ID the parts of a wave: wavelength, amplitude,
crest, trough, compression, rarefaction, & rest position
Today’s Agenda:• Notes & PowerPoint• Waves Video Activity• Wave Exit Ticket
Waves• Have you ever been in a wave
pool at an amusement park? How do we know that energy is being transferred?
Mechanical waves• A mechanical wave is a ___________ in matter
that carries ______ from one place to another disturbance
• Energy is the ability to do _____work• Mechanical waves need a material to travel
through, which is called a ________medium
• A medium can be a solid, ____, or gas
In a wave pool, what is the medium?
liquid
water
energy
• A mechanical wave is created when a source of energy causes a vibration to travel through a medium
Mechanical waves
• Think about shaking a rope, when you shake the rope, you add energyo The wave that results carries energy along
the rope
• Mechanical waves are classified by the way they move through a medium
Mechanical waves
transverse
longitudinal
surface
3
Transverse wave• Before the wave, every point is @ resting
position • The highest point of the wave above the RP is
the _____• The lowest point below the RP is the ______
cresttrough• The crest and the trough are not fixed points
• A transverse wave is a wave that causes the medium to vibrate at right angles to the direction in which the wave travels
• Imagine shaking a rope attached to a chairoBy shaking the rope, you create waves that
move up and down oHowever, the energy is moving from left to
right oThese two
motions are perpendicular
to one another
Transverse wave
• Examples of transverse waves: o Shaking a rope up & down that is tied to
somethingo Shaking crumbs off of a blanket or sand off of
a beach towel o Stadium wave at football & basketball games
Transverse wave
transverse waves• In transverse waves, the vibration of the
medium is ___________ to the direction that the wave travels
perpendicular
Longitudinal waves
• However, in a longitudinal wave, the vibration of the medium is parallel to the direction the wave travels
Draw:
rarefaction
compression
Longitudinal waves• To start a LW, add energy via pushing &
pulling o carries energy from left to right, coils
move closer together or farther apart
Longitudinal waves• Think about a slinky or a springoWhen you push it together and pull it apart, a
wave is sent through the slinky oEach coil in the slinky vibrates back-and-forth,
the wave also travels back-and-forthoTherefore, the motion of the vibration is
parallel to the direction the wave moves
• Label each section as a compression or rarefaction
Longitudinal waves
A
B
C
D
E
• Remember, oA compression is an area where the particles
in a medium are spaced ______ togetheroA rarefaction is an area where the particles in
a medium are _______ ____
close
spread
out
rarefaction
compression
compression
rarefaction
compression
Surface waves • The first waves you probably think of is ocean
waves, which are called surface waves
• A surface wave is a wave that travels along a surface separating two media
• Ocean waves travel between water & air
• A bobber in the ocean moves up & down (perpendicular) and back & forth (parallel) producing a circular motion
• Most waves do not transfer matter from one place to another
• However, as a wave enters shallow water, it topples over on itself
• Why do you think this happens?
Surface waves
• Friction with the show slows down the bottom of the wave
• The top of the wave continues forward at its original speed
Properties of mechanical waves
• How do we describe waves?
• If you like to surf, fish, or just swim in the ocean – you should know a little something about describing waves...
3 ft. at 8s SE 2 ft. at 14s NE
• Wavelength is the distance between a point on one wave & the same point on the next cycle of the wave
Properties of MWs
Wavelength
Wavelength • The distance between a point on one wave and
the same point on then next cycle of the wave
Which wave has longer wavelengths?
A
B
https://www.youtube.com/watch?v=aH5r4ZTOXS4
Amplitude
• The more ______ a wave has, the greater its amplitude
• Amplitude of a wave is the maximum displacement of the medium from its rest position
energy
Waves Video Activity• For this activity, students will work in groups
of 4-5 to create a 3-5 minute video explaining the 3 types of mechanical waves discussed today
• In the video, students should illustrate and define: mechanical wave, transverse wave, trough, crest, rest position, longitudinal wave, compression, rarefaction, surface wave, medium, wave length, & amptliude
Exit Ticket pg. 1001. Draw a transverse wave. Label the crest,
trough, amplitude, and wavelength. 2. Draw a longitudinal/compressional wave.
Label an area of compression and rarefaction.
3. Give an example of a surface wave. 4. In what type of wave does the medium
travel perpendicular to the motion of energy?
5. In what type of wave des the medium travel parallel to the motion of energy?