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

Wave Diagram

Rest position

Crest

Trough

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

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

Longitudinal waves• Slinky Drop Experiment: https://www.youtube.com/watch?v=wGIZKETKKdw

• 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

Longitudinal waves• Examples?oSound wavesoP waves

(earthquake)

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

Surface waves

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• Amplitude of a wave is the maximum

displacement of the medium from its rest position

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?