The Big Idea Waves transmit energy through space and time. Vibrations and Waves The Big Idea Waves transmit energy through space and time.

Make that “wiggle” move through space, and you have a wave Make that “wiggle” move through space, and you have a wave! [A disturbance that is transmitted progressively from one place to the next with no actual transport of matter] A “wiggle” in time is called a vibration. [A repeating, back-and- forth motion about an equilibrium position]

Vibration of a Pendulum 25.1 Galileo discovered the concept of a period by using a pendulum. Pendulum: a weight hung from a fixed point so that it can swing freely backward and forward. THINK SHUTTLE RUN!!

Vibration of a Pendulum 25.1 The time of a back-and-forth swing of a pendulum is called the period. Depends on length of pendulum Acceleration due to gravity Longer Pendulum = Longer Period Shorter Pendulum = Shorter Period What determines the period of a pendulum? Galileo concurred that the time a pendulum takes to swing back-and-forth depends only on the length of the pendulum- the mass has NO effect.

represented by a SINE curve. Wave Description 25.2 The back and forth vibratory motion (oscillatory motion) of a swinging pendulum is called Simple Harmonic Motion. The source of all waves is something that vibrates! Harmonic Motion: is represented by a SINE curve.

Wave Description 25.2 Sine Curve= Pictorial representation of a wave

Wave Description 25.2 - The high points on a wave are called the crests. - The low points on a wave are called the troughs. - The origin is also known as the “home” position or midpoint of the vibration. The amplitude equals the maximum displacement from equilibrium. The distance between successive identical parts of the wave is known as the wavelength.

Wave Description 25.2 Frequency: The number of vibrations (wiggles) an object makes in a unit of time. Specifies the number of back-and-forth vibrations a pendulum (or spring) makes [usually in one second]. A complete back-and-forth vibration is 1 cycle.

Wave Description 25.2 Frequency is measured in cycles per second or Hertz (Hz). NOTICE that frequency and period are related: Frequency = 1 / period Period = 1 / frequency Therefore they are inverses of each other! The Willis Tower (Sears) sways back and forth at a frequency of 0.1 Hz. What is its period of vibration? What is the source of all waves?

Wave Motion 25.3 A wave is a disturbance that transmits energy- not matter! Sound is energy that travels to our ears in the form of waves. Light is energy that comes to our eyes in the form of an electromagnetic wave. The energy transferred by a wave from a vibrating source to a receiver is carried by a disturbance in a Medium.

Wave Speed 25.4 The speed of a wave depends on the medium through which the wave moves. Whatever the medium, the speed, wavelength, and frequency of the wave are related. Calculating Speed of Wave: 𝒗=𝝀𝒇 v = wave speed (m/s) 𝝀 = GREEK- lambda- wavelength (m) f = wave frequency (Hz)

Types of Waves (25.5 & 25.6) Transverse Waves Longitudinal Waves Waves move parallel to the wave disturbance and are made up of compressions and rarefactions (expansions). *push in and pull out* Waves move perpendicular to the wave disturbance and are made up of crests and troughs. *shaking a rope up and down*

Transverse Waves- In Real Life

Longitudinal Waves- In Real Life

Wave Interference 25.7 Interference Patterns occur when waves (from differnet sources) arrive at the same point- at the same time. Destructive- crests overlap, effects are reduced. The high part of one wave simply fills in the low part of another: cancellation. Constructive- crests overlap, effects are added together. The result of the waves are added together: increasing amplitude.

Wave Interference 25.7 Constructive Interference * When 2 crests arrive at the same time * The 2 crests move the wave upwards to make a larger wave (waves add together) Wave Pulses Move THROUGH One Another

Wave Interference 25.7 Destructive Interference *When 1 crest and 1 trough arrive at the same time and cancel each other out if they are identical in size (temporarily). *Partially destructive waves may not cancel each other but dampen the wave temporarily.

CONSTRUCTIVE INTERFERENCE Individual Amplitude- 1 unit Construction = 2 units (added together)

CONSTRUCTIVE INTERFERENCE Individual Amplitude- 1 unit Construction = 2 units (added together)

COMPLETE DESTRUCTIVE INTERFERENCE Individual Amplitudes = 1 unit Destructive Interference = 1-1 or 0 units

DESTRUCTIVE INTERFERENCE (NOT COMPLETE) Individual Amplitude- 1 unit (red), 2 units blue) Destruction = 2 units – 1 unit = 1 unit of interference

Wave Interference 25.7

Standing Waves 25.8 When two pulses with equal but opposite amplitudes meet. The waves have the same shape, amplitude and wavelength but opposite directions. Nodes are the stationary points on a standing wave. (completely undisturbed) Antinodes are where the amplitudes are largest (occurs between nodes). Standing waves can be produced in either transverse or longitudinal waves.

Standing Waves 25.8

The Doppler Effect 25.9- Sound As a wave source approaches, an observer encounters waves with a higher frequency. Lower frequency as the source moves away. An apparent change in frequency due to the motion of the source. The greater the speed of the source, the greater will be the effect.

The Doppler Effect 25.9- Light As a light source approaches, there is an increase in frequency. When it recedes, there is a decrease in frequency. Increased frequency = blue shift High- frequency = end of color spectrum Decreased frequency = red shift Low- frequency = end of color spectrum

Bow Waves & Shock Waves 25.9.10 Bow Wave Shock Wave When speed of source is as great as speed of waves, the waves pile up or overlap. It appears that the waves are dragging behind. When an object moves faster than the speed of sound. The sharp crack that sweeps behind a supersonic aircraft Is called a sonic boom.

The Big Idea Waves transmit energy through space and time. Vibrations and Waves The Big Idea Waves transmit energy through space and time.

Make that “wiggle” move through space, and you have a wave Make that “wiggle” move through space, and you have a wave! [A disturbance that is transmitted progressively from one place to the next with __________ ______________________] A “wiggle” in time is called a vibration. [___________________ ____________________ __________________]

Vibration of a Pendulum 25.1 __________ discovered the concept of a period by using a pendulum. Pendulum: a weight hung from a fixed point so that it can swing freely backward and forward. THINK SHUTTLE RUN!!

Vibration of a Pendulum 25.1 The time of a back-and-forth swing of a pendulum is called the period. Depends on __________________ ____________________________ Longer Pendulum = Longer Period Shorter Pendulum = Shorter Period What determines the period of a pendulum? ___________________ ______________________________ Galileo concurred that the time a pendulum takes to swing back-and-forth depends only on the length of the pendulum- ______________________.

represented by a _______ curve. Wave Description 25.2 The back and forth vibratory motion (oscillatory motion) of a swinging pendulum is called ___________________________. The source of all waves is something that vibrates! Harmonic Motion: is represented by a _______ curve.

Wave Description 25.2 Sine Curve= Pictorial representation of a wave

Wave Description 25.2 - The high points on a wave are called the _________. - The low points on a wave are called the __________. - The origin is also known as the “home” position or __________ of the vibration. The ___________ equals the maximum displacement from equilibrium. The distance between successive identical parts of the wave is known as the _________.

Wave Description 25.2 Frequency: The number of ______________________________________ ________________. Specifies the number of back-and-forth vibrations a pendulum (or spring) makes [usually in one second]. A complete back-and-forth vibration is 1 cycle.

Wave Description 25.2 Frequency is measured in ______________ or Hertz (Hz). NOTICE that frequency and period are related: Frequency = ____________ Period = ______________ Therefore they are inverses of each other! The Willis Tower (Sears) sways back and forth at a frequency of 0.1 Hz. What is its period of vibration? What is the source of all waves?

Wave Motion 25.3 A wave is a disturbance that transmits energy- _____________! Sound is energy that travels to our ears in the form of waves. Light is energy that comes to our eyes in the form of an electromagnetic wave. The energy transferred by a wave from a vibrating source to a receiver is carried by a disturbance in a __________.

Wave Speed 25.4 The speed of a wave depends on the medium through which the wave moves. Whatever the medium, the speed, wavelength, and frequency of the wave are related. Calculating Speed of Wave: 𝒗=𝝀𝒇 v = ______________________ 𝝀 = ______________________ f = ______________________

Types of Waves (25.5 & 25.6) Transverse Waves Longitudinal Waves Waves move ____________to the wave disturbance and are made up of compressions and rarefactions (expansions). *push in and pull out* Waves move ____________ to the wave disturbance and are made up of crests and troughs. *shaking a rope up and down*

Transverse Waves- In Real Life

Longitudinal Waves- In Real Life

Wave Interference 25.7 Interference Patterns occur when waves (from differnet sources) arrive at the same point- at the same time. Destructive- crests overlap, effects are reduced. The high part of one wave simply fills in the low part of another: ________________________. Constructive- crests overlap, effects are added together. The result of the waves are added together: __________________________.

Wave Interference 25.7 Constructive Interference * Wave Pulses Move THROUGH One Another

Wave Interference 25.7 Destructive Interference *

CONSTRUCTIVE INTERFERENCE Individual Amplitude- 1 unit Construction = 2 units (added together)

CONSTRUCTIVE INTERFERENCE Individual Amplitude- 1 unit Construction = 2 units (added together)

COMPLETE DESTRUCTIVE INTERFERENCE Individual Amplitudes = 1 unit Destructive Interference = 1-1 or 0 units

DESTRUCTIVE INTERFERENCE (NOT COMPLETE) Individual Amplitude- 1 unit (red), 2 units blue) Destruction = 2 units – 1 unit = 1 unit of interference

Wave Interference 25.7

Standing Waves 25.8 When two pulses with equal but opposite amplitudes meet. The waves have the same shape, amplitude and wavelength but opposite directions. ___________ are the stationary points on a standing wave. (completely undisturbed) ___________ are where the amplitudes are largest (occurs between nodes). Standing waves can be produced in either transverse or longitudinal waves.

Standing Waves 25.8

The Doppler Effect 25.9- Sound As a wave source approaches, an observer encounters waves with a ___________________. Lower frequency as the source moves away. An apparent change in frequency due to the motion of the source. The greater the speed of the source, the greater will be the effect.

The Doppler Effect 25.9- Light As a light source approaches, there is an increase in frequency. When it recedes, there is a decrease in frequency. Increased frequency = __________ High- frequency = end of color spectrum Decreased frequency = _________ Low- frequency = end of color spectrum

Bow Waves & Shock Waves 25.9.10 ____________ _______________ When speed of source is as great as speed of waves, the waves pile up or overlap. It appears that the waves are dragging behind. When an object moves faster than the speed of sound. The sharp crack that sweeps behind a supersonic aircraft Is called a sonic boom.