Unit 4, Chapter 12

Integrated Science

2

Waves are everywhere in nature

Sound waves, visible light

waves, radio waves, microwaves, water waves,

telephone chord waves,

stadium waves,

earthquake waves,

waves on a string,

slinky waves

12.1 Why study about waves?

useful puzzling

4

What is a wave?

*A wave is a disturbance that travels through a medium from one location to another.

*A wave is the motion of a disturbance

Examples: Waves in water; Seismic waves in the Earth

Read intro page 201

12.1 Waves If we poke a ball floating on

water, it will bob up and down (harmonic motion).The oscillating ball creates a wave on the water surface.— What is oscillation?Oscillation is a system of harmonic motion The first ball can make a second ball that is farther away oscillate. (move)

Explain the transfer of energy.

Read page 201

Water Demo

12.1 Waves *Harmonic Motion: Motion that

repeats itself. Like a ball bobbing up and down in the water

*What is oscillation?Oscillation is a system of harmonic motion Example: The first ball can make a second ball that is farther away oscillate. (move)

Read page 201

Water Demo

12.1 Evidence of wavesAnytime you see a vibration that movesAnything that makes or responds to sound Anything that makes or responds to light Anything that transmits information through the air

(or space) without wires— cell phones, radio, and television.

Anything that allows you to “see through” objects— ultrasound, CAT scans, MRI scans, and X rays

Read page 202

1. When you transmit information without anything obviously moving, you are using waves.A. Yes

B. No

2. How many different types of waves are there?

2.0

0.1

There are Two Types of Waves:1. *A transverse wave has its oscillations

perpendicular to the direction the wave moves.

(In other words: the wave bobs up and down)

Read page 203

3. [Enter question here]

A. True

B. False

2. *A longitudinal wave has its oscillations in the same direction as the wave moves.

There are Two Types of Waves:

Read page 203

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*Longitudinal Wave

The wave we see here is a longitudinal wave.The medium particles vibrate parallel to the

motion of the pulse.*This is the same type of wave that we use to

transfer sound.Can you figure out how?? show tuning fork demo

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Compare/Contrast Wave Types

The difference between the two types:

These are transverse waves.

A. True

B. False

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This is a transverse wave:

A. True

B. False

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Sound travels through a longitudinal wave.

A. True

B. False

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Anatomy of a WaveNow we can begin to describe the

anatomy of our waves.We will use a transverse wave to describe

this since it is easier to see the pieces.

Read page 204

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*Anatomy of a Wave

*In our wave here the dashed line represents the equilibrium position.

Once the medium is disturbed, it moves away from this position and then returns to it

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Anatomy of a Wave

The points A and F are called the CRESTS of the wave.

*The crest is the point where the wave exhibits the maximum amount of positive or upwards displacement. (the top of the wavelength)

crest

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Anatomy of a Wave

The points D and I are called the TROUGHS of the wave.

*The troughs are the points at the bottom of wavelength)

trough

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Anatomy of a Wave

*The distance between the dashed line and point A is called the Amplitude of the wave.\

This is the maximum displacement that the wave moves away from its equilibrium.

Amplitude

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Anatomy of a Wave

The distance between two consecutive similar points (in this case two crests) is called the wavelength.

*The wavelength is the length of the wave pulse.Between what other points is can a wavelength be

measured?

wavelength

4. There are two ways to measure a wave: from crest to

crest or trough to trough.A. True

B. False

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Wave frequency

We know that frequency measure how often something happens over a certain amount of time.

We can measure how many times a pulse passes a fixed point over a given amount of time, and this will give us the frequency.

Wave Frequency* The frequency of a wave is a measure

of how often it goes up and down.*Wave frequency is measured in hertz.

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Frequency, Amplitude and Wavelength

12.1 Wavelength

*Speed of a Wave:

v = f l

frequency (cycles/sec)

wavelength (m)

*speed (m/sec)

5. What is the speed of a wave that has a frequency of 10 hz and a wavelength of 50 m?

500.0

0.1

6. What is the speed of a wave that has a frequency of 5 hz and a wavelength of 30 meters?150.0

0.1

The frequency of a wave is how often it goes up and down.

A. True

B. False

The amplitude of a wave is the largest amount it goes above or below the equilibrium.

A. True

B. False

Waves are measured in joules.

A. True

B. False

Waves transfer energy through the disturbance of a medium.

A. True

B. False

Frequency is the measurement of height of a wave.

A. True

B. False

Sound is carried through transverse waves.

A. True

B. False

Your Turn:

Answer these questions with a partner:

1. Which of the following things must involve a wave? You may pick more than one. Explain each of your choices.a) A bulldozer is moving the dirt for a highwayb) A person is talking to someone on a cell phonec) An earthquake in the Pacific Ocean causes a house to

shake in Texasd) A car is going 70 miles per hour on a highwaye) Two people stop to listen to a jet passing overheadf) A doctor takes an X ray to check for broken bones

2. Draw a Transverse Wave. Label the a wavelength, amplitude, crest and trough.

Anatomy of a Wave: