7 th grade Notes Week 17- Monday Waves Intro. Waves Intro: what it is… C-notes A wave is a...
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Transcript of 7 th grade Notes Week 17- Monday Waves Intro. Waves Intro: what it is… C-notes A wave is a...
7th grade Notes Week 17-Monday
Waves Intro
Waves Intro: what it is…
C-notes
A wave is a disturbance caused by a forceExample: you drop a pebble in water, a wave is formed
Waves: What do they do?C-notes
Waves transfer ENERGYThe molecules of the MEDIUM do NOTMove to another place…
Waves Intro: Causes & Examples
C-notes
a)Water waves…caused by wind (some by Earthquakes- tsunami)
b)Ground shakes because pressure is released (EARTHQUAKE)
c)You hit something it vibrates making a sound. Sound moves in waves
Waves Intro: Types of waves
C-notes
There are two types of waves:Mechanical and Electromagnetic
Waves Intro: Mechanical
C-notes
Mechanical waves are waves that move in MATTER.If there is no “MATTER”; there is no movementMEDIUM- is any type of matter that mechanical waves move in
Mechanical Wave: An example
C-notes
•Sound is an example of a mechanical wave.•Sound is produced by vibrations•The energy from the vibration moves in waves•Sound can ONLY travel if there is a medium
Waves Intro: Electromagnetic
C-notes
Electromagnetic waves can move through “empty” space. A place with little or no molecules is called a vacuum
Parts of a Transverse wave
C-notes
Crest- highest point of the wave
Trough (troff)- lowest point of the wave
REST LINEIf there were no energy…
Types of mechanical waves
C-notes
Transverse waves are waves in which the movement of the vibrating particles is perpendicular to the direction of the wave.Example:Water wave
Types of mechanical waves
C-notes
Longitudinal waves are waves in which the movement of the vibrating particles is parallel to the direction of the wave.Example: sound wave
Properties of (ALL) Waves
Frequency:How many crests pass in a second
Amplitude:Measure from rest line to crest
Wavelength:Measure from one crest to the next
AmplitudeWhat does it measure?
Diagram of what it measures
Wavelength What does it measure?
Diagram of what it measures
Frequency What does it measure?
Diagram of what it measures
The energy of the wave.The more amplitude the more energy.
The distance between one crest and another
The number of vibrations (waves) each second.Unit used: hertz
Sound Energy C-notes
Sound energy is the energy of vibration
Sound produces an mechanical wave- it needs a medium to move in
Sound Energy C-notes
Sound waves are LONGITUDINAL waves
Another name for longitudinal waves is a COMPRESSION wave
Sound Energy C-notes
Sound waves have the same properties as waves (amplitude, wavelength, frequency)However there are two “parts” to a COMPRESSION wave
Sound Energy C-notes
Compression- where molecules of medium and pressed together
Rarefaction- where molecules of a medium spread apart
Hearing and Wave properties
C-notes
Our ears can sense the amplitude of a sound wave
The more energy, the more amplitude.
Hearing and Wave properties
C-notes
The greater amplitude is sensed as INTENSITY (LOUDNESS)
The sound intensity is measured with a unit called decibel
Hearing and Wave properties
C-notes
Our ears can sense frequency of the vibration
The more vibrations, the higher the frequency. This is a high pitch sound
Hearing and Wave properties
C-notes
Our ears can sense frequency of the vibration
The more vibrations, the higher the frequency. This is a high pitch sound
Hearing and Wave properties
C-notes
Frequency is measured in a unit called HERTZ (Hz). These are vibrations per second
We can “hear” 20 hertz to 20,000 hertz