Unit 5, Part 1:SOUND

WAVESSWBAT explain how waves are created and identify the different types of waves

What do you already know about sound and waves? (10 minutes total)

1. Create a CIRCLE thinking map2. Write “Sound & Waves” in the center3. Think about your point of views. Where have

you learned about sound and waves before?4. What words, images, or examples come to

mind?5. SHARE your thinking map with a partner.6. DISCUSS as a class.

Sound Waves Video (5 minutes)

Key ideas in this PowerPoint will be in RED

Thinking about sound• Sound waves must go through a medium• The medium is made up particles– Mediums can be solid, liquid, or gas

• Waves cause particles to vibrate and create sound

• A wave occurs when there is a disturbance in a medium

Vibrations

Sound is a form of energy that is produced by vibration (back-and-forth movement)

Vibration ExamplesWhen we talk, our vocal chords move.

When we play the guitar, the string moves

When you hit a drum, the drumhead moves

When we talk, our vocal chords move.

Each of these movement is a back-and-forth movement called a vibrationAny more examples?

Properties of Sound

Amplitude: how loud or soft a sound is. Measured by how

much the medium is disturbed

Amplitude Determines

Loudness

Amplitude Determines LoudnessHigher Amplitude = LouderLower Amplitude = Softer

Example: you can beat a drum with different levels of intensity. The harder you beat the drum, the more vibrations, and thus a

greater amplitude.

Loudness & Softness: The

numbers represent “decibels,” or “db.” The human ear can hear from 0db’s to

about 110db’s comfortably.

120db’s or more could result in ear

damage.

Frequency of WavesFrequency is the number of waves

produced in a given time

Types of waves

• If a wave moves perpendicular to the motion of the particle, this is called a transverse wave

Types of waves• Longitudinal waves occur when a string is

compressed and stretched.

• The stretched and compressed regions travel along the spring

• Sound waves are longitudinal because particles move parallel to wave motion

Longitudinal Waves (The Slinky Wave)• When the slinky is pressed together, we call

this compression• When the slinky is stretched, we call this

rarefaction

Parts of a wave

• Crest• Trough• Resting Point• Wavelength (λ) • Amplitude

CREST

THE CREST IS THE HIGHEST PART OF THE WAVE!

TROUGH

THE TROUGH IS THE LOWEST PART OF THE WAVE

RESTING POINT

Point “C” represents the dashed line.The dashed line is this wave’s resting point.

WAVE HEIGHT

THE DISTANCE BETWEEN WAVE HEIGHT AND WAVE

TROUGH

WAVE PERIOD

THE TIME IT TAKES FOR ONE WAVE TO PASS

Example 1

Example 2: You can see this same thing in the ocean

Example 3

Measuring Waves

• Frequency: the number of waves that pass a given point over a unit of time

• Period: time required for one complete wavelength to pass a given point

The distance between points A and point B is the “wave length”

And remember, math and science are ALWAYS related…

f = 1 or T = 1 T

fFrequency (f) = hertz (H)Period (T) = seconds (s)

frequency and period have an inverse relationship

Wave Speed

• We can determine wave speed using wavelength and frequency

v = fλ

V = wave speedf = frequency

λ = wavelength

But, don’t worry about those calculations!

…YET!

Exit Ticket

1. Draw a wave and label the CREST, TROUGH, and RESTING point

2. In one sentence, explain how one would calculate a wave’s height

3. In one sentence, explain how one would calculate wave length

4. Sounds need to travel through a __________.5. What is wave amplitude?6. Write a 3-5 sentence summary about today’s lesson.