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Motion

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Title: Motion


1
Motion
2
Aristotle
  • 4 elements that are the building blocks of the
    world around us _______________,
    _______________, _______________, _______________
  • Rock belongs to the earth element, would fall
    back to the earth
  • Smoke belongs to the fire element, rises above
    air

3
Aristotle
  • _______________ Motion straight up and straight
    down motion
  • Circular motion is the natural motion of the
    heavens all the planets revolve around the
    earth
  • _______________ Motion result of forces that
    pushed or pulled from some external cause
  • Cart being pulled by a horse

4
Copernicus
  • Studied the planets
  • Earth and the other planets move around the sun.
  • Worked on this idea in secret to escape
    persecution.
  • The day he died, he received his work in print
    (1543)

5
Galileo
  • Expanded on Copernicus ideas
  • Brought in the concept of ______________
  • Time for the motion to happen

6
  • A study of motion will involve the introduction
    of a variety of quantities which are used to
    describe the physical world.
  • Examples of such quantities include distance,
    displacement, speed, velocity, acceleration,
    force, mass, momentum, energy, work, power, etc.

7
  • All these quantities can by divided into two
    categories
  • _______________
  • A vector quantity is a quantity which is fully
    described by both magnitude and direction.
  • _______________
  • A scalar quantity is a quantity which is fully
    described by its magnitude.

8
Vector Quantities
  • _______________
  • _______________
  • _______________
  • _______________

9
Linear Motion
  • Motion in a straight line
  • _______________ measure of how fast something
    is moving
  • mph
  • _______________ speed in a given direction
  • m/s northward
  • _______________ the rate at which velocity is
    changing
  • m/s2
  • Can be positive or negative

10
Projectile Motion
  • The most common example of an object which is
    moving in two-dimensions is a _______________.
  • A projectile is an object upon which the only
    force acting is _______________.

11
  • A projectile is any object which once projected
    _______________ in motion by its own inertia and
    is influenced only by the downward force of
    gravity.
  • an object dropped from rest is a projectile
    (provided that the influence of air resistance is
    negligible)
  • an object which is thrown vertically upwards is
    also a projectile (provided that the influence of
    air resistance is negligible)
  • an object is which thrown upwards at an angle is
    also a projectile (provided that the influence of
    air resistance is negligible).

12
(No Transcript)
13
Horizontally Launched Projectiles
  • Imagine a cannonball being launched from a cannon
    atop of a very high cliff. Imagine as well that
    the cannonball does not encounter a significant
    amount of air resistance. What will be the path
    of the cannonball and how can the motion of the
    cannonball be described?

14
  • The animation below depicts such a situation. The
    path of the cannonball is shown additionally,
    the horizontal and vertical velocity components
    are represented by arrows in the animation.

15
  • As the cannonball falls, it undergoes a downward
    acceleration. A downwardly-moving cannonball
    which is gaining speed is said to have a downward
    acceleration.
  • This downward acceleration is attributed to the
    downward force of gravity which acts upon the
    ball.

16
Acceleration Due to Gravity
  • Galileo objects fall at the same rate
  • Did recognize that a compact object does fall
    faster than a less compact object (flat paper vs.
    crumpled paper)
  • Acceleration due to gravity (g) 9.8 m/s2
  • Objects fall with the same _______________ but it
    will be dependent on _______________
  • 1971, David Scott, US Astronaut, dropped a hammer
    and a feather on the moon and they hit the
    surface of the moon at the same time

17
Newtons First Law of Motion
  • an object in motion continues in motion with the
    same speed and in the same direction unless acted
    upon by an unbalanced force.
  • It is the natural tendency of objects to keep on
    doing what they're doing.

18
  • All objects _______________ in their state of
    motion.
  • In the absence of an unbalanced force, an object
    in motion will maintain this state of motion.
    This is often called the _______________.
  • Inertia is the _______________ an object has to a
    change in its state of motion. Inertia is
    dependent only on _______________.

19
  • At the time, Newton's concept of inertia was in
    direct opposition to the more popular conceptions
    about motion.
  • The dominant thought prior to Newton's day was
    that it was the natural tendency of objects to
    come to rest.
  • Moving objects, or so it was believed, would
    eventually stop moving since a force was
    necessary to keep an object moving.
  • If left to itself, a moving object would
    eventually come to rest and an object at rest
    would stay at rest thus, the idea which
    dominated the thinking for nearly 2000 years
    prior to Newton was that it was the natural
    tendency of all objects to assume a rest
    position.

20
  • Newton's first law of motion declares that a
    _______________ is not needed to keep an object
    in motion.
  • Slide a book across a table and watch it slide to
    a stop.
  • The book in motion on the table top does not come
    to rest because of the absence of a force rather
    it is the presence of a force the force of
    _______________ which brings the book to a
    halt.

21
  • The law of inertia is most commonly experienced
    when riding in cars and trucks.
  • In fact, the tendency of moving objects to
    continue in motion is a common cause of a variety
    of transportation accidents - of both small and
    large magnitudes.

22
  • Consider for instance the unfortunate collision
    of a car with a wall.
  • Upon contact with the wall, an unbalanced force
    acts upon the car to abruptly decelerate it to
    rest.
  • Any passengers in the car will also be
    decelerated to rest if they are strapped to the
    car by seat belts. Being strapped tightly to the
    car, the passengers share the same state of
    motion as the car.

23
  • As the car accelerates, the passengers accelerate
    with it as the car decelerates, the passengers
    decelerate with it and as the car maintains a
    constant speed, the passengers maintain a
    constant speed as well.

24
  • But what would happen if the passengers were not
    wearing the seat belt? What motion would the
    passengers undergo if they failed to use their
    seat belts and the car were brought to a sudden
    and abrupt halt by a collision with a wall?

25
  • Were this scenario to occur, the passengers would
    no longer share the same state of motion as the
    car. The presence of the strap assures that the
    forces necessary for accelerated and decelerated
    motion exist. Yet, once the strap is no longer
    present to do its job, the passengers are more
    likely to maintain its state of motion.

26
  • If the car were to abruptly stop and the seat
    belts were not being worn, then the passengers in
    motion would continue in motion. Assuming a
    negligible amount of friction between the
    passengers and the seats, the passengers would
    likely be propelled from the car and be hurled
    into the air. Once they leave the car, the
    passengers becomes projectiles and continue in
    projectile-like motion.

27
  • But why then are motorcycles not equipped with
    safety harnesses? Is this a gross oversight made
    by motorcycle manufacturers?

28
There are many more applications of Newton's
first law of motion.
  • blood rushes from your head to your feet when
    riding on a descending elevator which suddenly
    stops.
  • the head of a hammer can be tightened onto the
    wooden handle by banging the bottom of the handle
    against a hard surface.
  • a brick is painlessly broken over the hand of a
    physics teacher by slamming the brick with a
    hammer. (CAUTION Do not attempt this at home!)
  • to dislodge ketchup from the bottom of a ketchup
    bottle, the bottle is often turned upside down,
    thrust downward at a high speed and then abruptly
    halted.
  • headrests are placed in cars to prevent whiplash
    injuries during rear-end collisions.
  • while riding a skateboard (or wagon or bicycle),
    you fly forward off the board when hitting a
    curb, a rock or another object which abruptly
    halts the motion of the skateboard.

29
  • 1. Imagine a place in the cosmos far from all
    gravitational and frictional influences. Suppose
    an astronaut in that place throws a rock. The
    rock will
  • 2. Mac and Tosh are arguing in the cafeteria. Mac
    says that if he throws his jello with a greater
    speed it will have a greater inertia. Tosh argues
    that inertia does not depend upon speed, but
    rather upon mass. With whom do you agree? Why?

30
  • 3. If you were in a weightless environment in
    space, would it require a force to set an object
    in motion?
  • 4. Mr. Wegley spends most Sunday afternoons at
    rest on the sofa, watching pro football games and
    consuming large quantities of food. What effect
    (if any) does this practice have upon his
    inertia? Explain.

31
  • Ben Tooclose is being chased through the woods by
    a bull moose which he was attempting to
    photograph. The enormous mass of the bull moose
    is extremely intimidating. Yet, if Ben makes a
    zigzag pattern through the woods, he will be able
    to use the large mass of the moose to his own
    advantage. Explain this in terms of inertia and
    Newton's first law of motion.

32
Newtons Second Law of Motion
  • Objects at _______________ (the condition in
    which all forces balance) will not accelerate.
  • According to Newton, an object will only
    accelerate if there is a net or unbalanced force
    acting upon it.
  • Newton's second law of motion pertains to the
    behavior of objects for which all existing forces
    are not balanced.

33
  • The second law states that the acceleration of an
    object is dependent upon two variables the net
    force acting upon the object and the mass of the
    object.
  • As the net force increases, so will the object's
    acceleration. However, as the mass of the object
    increases, its acceleration will decrease.

34
  • Fnet ma
  • 1 Newton amount of force needed to move a 1 kg
    object 1 m/s2

35
Misconception of Motion
  • The idea that sustaining motion requires a
    continued force.

36
Newtons Third Law of Motion
  • "For every action, there is an equal and opposite
    reaction."

37
  • The statement means that in every interaction,
    there is a pair of forces acting on the two
    interacting objects.
  • The size of the force on the first object equals
    the size of the force on the second object.
  • The direction of the force on the first object is
    opposite to the direction of the force on the
    second object. _______________ always come in
    pairs equal and opposite action-reaction force
    pairs.

38
  • While driving, Anna Litical observed a bug
    striking the windshield of her car. Obviously, a
    case of Newton's third law of motion. The bug hit
    the windshield and the windshield hit the bug.
    Which of the two forces is greater the force on
    the bug or the force on the windshield?

39
  • 2. Rockets are unable to accelerate in space
    because ...
  • a. there is no air in space for the rockets to
    push off of.
  • b. there is no gravity is in space.
  • c. there is no air resistance in space.
  • d. ... nonsense! Rockets do accelerate in
    space.

40
Momentum
  • _______________ in motion
  • Mass x Velocity
  • The greater the _______________ acting on an
    object, the greater the change in the velocity,
    and the greater the change in momentum.
  • The more _______________ which an object has, the
    harder that it is to stop.

41
  • From the definition of momentum, it becomes
    obvious that an object has a large momentum if
    either its mass or its velocity is large.
  • Consider a Mack truck and a roller skate moving
    down the street at the same speed. The
    considerably greater mass of the Mack truck gives
    it a considerably greater momentum.
  • Yet if the Mack truck were at rest, then the
    momentum of the least massive roller skate would
    be the greatest for the momentum of any object
    which is at rest is 0.
  • Objects at rest do not have momentum - they do
    not have any "mass in motion."

42
Collisions
  • The physics of _______________ are governed by
    the laws of momentum and Newtons Laws.
  • In a collision, an object experiences a force for
    a specific amount of time which results in a
    change in momentum (the object's mass either
    speeds up or slows down).

43
  • In a collision, objects experience an
    _______________ the impulse causes (and is equal
    to) the change in momentum.
  • _______________ force x time (greater the
    impulse, the greater the change in momentum)

44
  • Observe that the _______________ the time over
    which the collision occurs, the _______________
    the force acting upon the object.
  • To minimize the effect of the force on an object
    involved in a collision, the time must be
    _______________
  • To maximize the effect of the force on an object
    involved in a collision, the time must be
    _______________.

45
Airbags in a Vehicle
  • Air bags are used in automobiles because they are
    able to minimize the effect of the force on an
    object involved in a collision.
  • Air bags accomplish this by extending the time
    required to stop the momentum of the driver and
    passenger.
  • The same principle explains why dashboards are
    padded.

46
  • When encountering a car collision, the driver and
    passenger tend to keep moving in accord with
    Newton's first law.
  • Their motion carries them towards a windshield
    which results in a large force exerted over a
    short time in order to stop their momentum.
  • If instead of hitting the windshield, the driver
    and passenger hit an air bag, then the time
    duration of the impact is increased.
  • When hitting an object with some give such as an
    air bag, the time duration might be increased by
    a factor of 100.
  • Increasing the time by a factor of 100 will
    result in a decrease in force by a factor of 100.

47
  • This same principle of padding a potential impact
    area can be observed in gymnasiums (underneath
    the basketball hoops), in pole-vaulting pits, in
    baseball gloves and goalie mitts, on the fist of
    a boxer, inside the helmet of a football player,
    and on gymnastic mats.

48
Effects of Rebounding
  • Occasionally when objects collide, they bounce
    off each other (as opposed to sticking to each
    other and traveling with the same speed after the
    collision).
  • Bouncing off each other is known as
    _______________.
  • Rebounding involves a change in direction of an
    object the before- and after-collision direction
    is different.

49
  • The importance of rebounding is critical to the
    outcome of automobile accidents.
  • In an automobile accident, two cars can either
    collide and bounce off each other or collide and
    crumple together and travel together with the
    same speed after the collision.

50
  • But which would be more damaging to the occupants
    of the automobiles - the rebounding of the cars
    or the crumpling up of the cars?

51
  • Contrary to popular opinion, the crumpling up of
    cars is the safest type of automobile collision.
  • If cars rebound upon collision, the momentum
    change will be larger and so will the impulse.
  • A greater impulse will typically be associated
    with a bigger force.
  • Occupants of automobiles would certainly prefer
    small forces upon their bodies during collisions.

52
  • In fact, automobile designers and safety
    engineers have found ways to reduce the harm done
    to occupants of automobiles by designing cars
    which crumple upon impact.
  • Automobiles are made with _______________.
  • Crumple zones are sections in cars which are
    designed to crumple up when the car encounters a
    collision.
  • Crumple zones minimize the effect of the force in
    an automobile collision in two ways.

53
  • By crumpling, the car is less likely to rebound
    upon impact, thus minimizing the _______________
    change and the _______________.
  • Finally, the crumpling of the car lengthens the
    _______________ over which the car's momentum is
    changed by increasing the time of the collision,
    the force of the collision is greatly reduced.

54
  • 1. Explain why it is difficult for a firefighter
    to hold a hose which ejects large amounts of
    high-speed water.

55
  • Would you care to fire a rifle that has a bullet
    ten times as massive as the rifle?

56
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57
No Seatbelt
  • Cars are designed with crumple zones so they may
    slow down over a longer period of time, which
    keeps the force smaller.  The crumple zone only
    slows the car more gradually.  The only way it
    slows the occupants more gradually is if they are
    attached to the car.  Stopping in a small amount
    of time means the force must be very large.  This
    video clip shows some very dramatic scenes of car
    crash tests with test dummies who are not wearing
    seat belts.  Specifically look for cars crumpling
    and people stopping in very small amounts of
    time. 

58
With Seatbelt
  • Seatbelts use two main ideas to protect
    passengers during a car accident.   First, they
    slow the passenger down more slowly than the
    passenger running into steering wheel or
    dashboard.  This keeps the force required to stop
    them smaller. It also prevents the person from
    contacting any of the glass windows in the car or
    continuing on to be stopped abruptly by the road,
    tree, or another automobile.  The video clip
    shows the role of the seatbelt during an accident

59
  • This clip clearly gives the driver a good reason
    to make sure occupants in the rear of the car are
    wearing their seat belts.  Not wearing a seatbelt
    not only puts your life in danger but also anyone
    else who happens to be riding with you.  The
    force from the seatbelt safely decelerates the
    driver, but the child in the back seat follows
    Newton's Law of Inertia and continues moving in
    the absence of a net force.  The 60mph "kid" not
    only breaks its own neck but also the neck of the
    driver.

60
  • In this clip, we see that seat belts and child
    seats not only protect you in a frontal impact,
    they could also prevent a tragedy in rear end
    collision.  In this clip, the station wagon
    literally gets accelerated out from under the
    "kids" sitting in the back.  They were at rest
    originally, and in the absence of a net force
    (from the seat belt) they remained at rest while
    the car they were in was accelerated by the net
    force from the car that hit them.  Newton's first
    law can be a killer!

61
Energy
62
  • What is energy?
  • The capacity to do _______________ or supply
    _______________.
  • Energy is weightless, odorless, and tasteless.
  • Energy is detected only because of its effects.
  • Heat is _______________ that transfers between
    objects across a temperature change.
  • Heat cannot be detected by the sense or by
    instruments only changes caused by heat can be
    detected.

63
Potential Energy
  • An object can store energy as the result of its
    position.
  • This stored energy of position is referred to as
    potential energy.
  • _______________ energy is the energy which an
    object has stored due to its position relative to
    some zero position.

64
Kinetic Energy
  • _______________ energy is the energy of motion.
  • An object which has motion - whether it be
    vertical or horizontal motion - has kinetic
    energy.
  • Standard metric unit of measurement for kinetic
    energy is the Joule.
  • 1 Joule is equivalent to 1 kg ? (m/s2).

65
  • The amount of kinetic energy which an object has
    depends upon two variables
  • the _______________ (m) of the object
  • the _______________ (v) of the object.

66
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67
Sound Waves
68
Transverse Wave
  • A _______________ wave is a wave in which
    particles of the medium move in a direction
    perpendicular to the direction which the wave
    moves.

69
Longitudinal Wave
  • A _______________ wave is a wave in which
    particles of the medium move in a direction
    parallel to the direction which the wave moves.

70
Comparison of the Two
71
Surface Wave
  • A _______________ wave is a wave in which
    particles of the medium undergo a circular
    motion. Surface waves are neither longitudinal
    nor transverse.
  • Waves which travel along the surface of the
    oceans.

72
  • Another way to categorize waves is on the basis
    of the ability (or nonability) to transmit
    _______________ through a _______________(i.e.,
    empty space).
  • Categorizing waves on this basis leads to two
    notable categories
  • electromagnetic waves
  • mechanical waves.

73
Electromagnetic Waves
  • An _______________ wave is a wave which is
    capable of transmitting its energy through a
    vacuum (i.e., empty space).
  • Electromagnetic waves are produced by the
    vibration of electrons within atoms on the Sun's
    surface.
  • These waves subsequently travel through the
    vacuum of outer space, subsequently reaching
    Earth.

74
  • All _______________ waves are examples of
    electromagnetic waves.

75
Mechanical Waves
  • A _______________ wave is a wave which is not
    capable of transmitting its energy through a
    vacuum.
  • Mechanical waves require a _______________ in
    order to transport their energy from one location
    to another.
  • A sound wave is an example of a mechanical wave.
    Sound waves are incapable of traveling through a
    vacuum.

76
  • Slinky waves, water waves, stadium waves, and
    telephone chord waves are other examples of
    mechanical waves each requires some medium in
    order to exist.
  • A slinky wave requires the coils of the slinky
  • a water wave requires water a stadium wave
    requires fans in a stadium
  • and a telephone chord wave requires a telephone
    chord.

77
  • _______________ is a wave which is created by
    vibrating objects and passed through a medium
    from one location to another.
  • The medium is simply the material through which
    the disturbance is moving it can be thought of
    as a series of interacting particles.

78
  • A sound wave is similar in nature to a slinky
    wave.
  • There is a medium which carries the disturbance
    from one location to another.
  • Typically, this medium is air though it could be
    any material such as water or steel.

79
  • Regardless of what vibrating object is creating
    the sound wave, the particles of the medium
    through which the sound moves is vibrating in a
    back and forth motion at a given _______________.
  • The frequency of a wave refers to how often the
    particles of the medium _______________ when a
    wave passes through the medium.
  • The frequency of a wave is measured as the number
    of complete back-and-forth vibrations of a
    particle of the medium per unit of time.

80
  • A commonly used unit for frequency is the
    _______________ (abbrviated Hz), where
  • 1 Hertz 1 vibration/second
  • As a sound wave moves through a medium, each
    particle of the medium vibrates at the same
    frequency.

81
  • The human ear is capable of detecting sound waves
    with a wide range of frequencies, ranging between
    approximately 20 Hz to 20 000 Hz.
  • Any sound with a frequency below the audible
    range of hearing (less than 20 Hz) is known as an
    _______________ and any sound with a frequency
    above the audible range of hearing (more than 20
    000 Hz) is known as an _______________.

82
  • Dogs can detect frequencies as low as
    approximately 50 Hz and as high as 45 000 Hz.
  • Cats can detect frequencies as low as
    approximately 45 Hz and as high as 85 000 Hz.
  • Bats, who are essentially blind and must rely on
    sound _______________ for navigation and hunting,
    can detect frequecies as high as 120 000 Hz.

83
  • Dolphins can detect frequencies as high as 200
    000 Hz.
  • While dogs, cats, bats, and dolphins have an
    unusual ability to detect ultrasound, an elephant
    possesses the unusual ability to detect
    infrasound, having an audible range from
    approximately 5 Hz to approxmately 10 000 Hz.

84
  • The sensations of these frequencies are commonly
    referred to as the ______________________________.
  • A high pitch sound corresponds to a high
    frequency and a low pitch sound corresponds to a
    low frequency.

85
  • The faintest sound which the human ear can detect
    is known as the _______________ _______________.
  • The most intense sound which the ear can safely
    detect without suffering any physical damage is
    more than one billion times more intense than the
    threshold of hearing.

86
  • Since the range of intensities which the human
    ear can detect is so large, the scale which is
    frequently used by physicists to measure
    intensity is a scale based on multiples of 10.
  • The scale for measuring intensity is the
    _______________.

87
Source Intensity Level
Threshold of Hearing (TOH) 0 dB
Rustling Leaves 10 dB
Whisper 20 dB
Normal Conversation 60 dB
Busy Street Traffic 70 dB
Vacuum Cleaner 80 dB
Large Orchestra 98 dB
Walkman at Maximum Level 100 dB
Front Rows of Rock Concert 110 dB
Threshold of Pain 130 dB
Military Jet Takeoff 140 dB
Instant Perforation of Eardrum 160 dB
  •  

88
  • At normal atmospheric pressure and a temperature
    of 20ºC, a sound wave will travel at
    approximately 343 m/s this is approximately
    equal to 750 miles/hour.
  • While this speed may seem fast by human
    standards, the speed of a sound wave is slow in
    comparison to the speed of a light wave.
  • Light travels through air at a speed of
    approximately 300 000 000 m/s this is nearly 900
    000 times the speed of sound.

89
Breaking the sound barrier
  • Accelerating past the speed of sound (750
    miles/hour)
  • _______________ - range of velocities just below
    and above the speed of sound.
  • When jets are in this transonic speed, they can
    create the vapor cone effect.

90
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91
Light Waves
92
"Is light a wave or a stream of particles?"
  • The fact is that light exhibits behaviors which
    are characteristic of both waves and particles.

93
  • All waves are known to undergo _______________ or
    the bouncing off of an obstacle.
  • Most people are very accustomed to the fact that
    light waves also undergo _______________.
  • The reflection of light waves off of a mirrored
    surface results in the formation of an image.

94
  • A light wave is an _______________ wave which
    travels through the vacuum of outer space.
  • Light waves are produced by vibrating electric
    charges.

95
  • Electromagnetic waves exist with an enormous
    range of frequencies. This continuous range of
    frequencies is known as the ______________________
    ________.
  • The entire range of the spectrum is often broken
    into specific regions.

96
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97
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98
  • Since this narrow band of wavelengths is the
    means by which humans see, we refer to it as the
    _______________ spectrum.
  • Normally when we use the term "light," we are
    referring to a type of electromagnetic wave which
    stimulates the retina of our eyes.

99
  • Each individual wavelength within the spectrum of
    visible light wavelengths is representative of a
    particular color.
  • When light of that particular wavelength strikes
    the retina of our eye, we perceive that specific
    color sensation.

100
  • Isaac Newton showed that light shining through a
    prism will be separated into its different
    wavelengths and will thus show the various colors
    that visible light is comprised of.
  • The separation of visible light into its
    different colors is known as _______________.

101
  • Dispersion of visible light produces the colors
  • red (R)
  • orange (O)
  • yellow (Y)
  • green (G)
  • blue (B)
  • indigo (I)
  • violet (V).
  • It is because of this that visible light is
    sometimes referred to as ROY G BIV

102
  • The red wavelengths of light are the
    _______________ wavelengths and the violet
    wavelengths of light are the _______________
    wavelengths.
  • When all the wavelengths of the visible light
    spectrum strike your eye at the same time,
    _______________ is perceived.
  • Visible light is sometimes referred to as
    _______________.

103
  • Technically speaking, white is not a color at
    all, but rather the combination of all the colors
    of the visible light spectrum.
  • If all the wavelengths of the visible light
    spectrum give the appearance of white, then none
    of the wavelengths would lead to the appearance
    of black.

104
  • Once more, black is not actually a color.
  • Technically speaking, black is merely the absence
    of the wavelengths of the visible light spectrum.
  • So when you are in a room with no lights and
    everything around you appears black, it means
    that there are no wavelengths of visible light
    striking your eye as you look at the
    surroundings.

105
  • The color of an object is not actually within the
    object itself rather, the color is in the light
    which shines upon it that ultimately becomes
    reflected or transmitted to our eyes.
  • We know that the visible light spectrum consists
    of a range of frequencies, each of which
    corresponds to a specific color.

106
  • When visible light strikes an object and a
    specific frequency becomes absorbed, that
    frequency of light will never make it to our
    eyes.
  • Any visible light which strikes the object and
    becomes reflected or transmitted to our eyes will
    contribute to the color appearance of that
    object.
  • So the color is not in the object itself, but in
    the light which strikes the object.

107
  • The only role that the object plays is that it
    might contain atoms capable of absorbing one or
    more frequencies of the visible light which shine
    upon it.
  • If an object absorbs all of the frequencies of
    visible light except for the frequency associated
    with green light, then the object will appear
    green.
  • And if an object absorbs all of the frequencies
    of visible light except for the frequency
    associated with blue light, then the object will
    appear blue.

108
  • When you look at an object and perceive a
    distinct color, you are not necessarily seeing a
    single frequency of light.
  • Consider for instance that you are looking at a
    shirt and it appears purple to your eye.
  • In such an instance, there my be several
    frequencies of light striking your eye with
    varying degrees of intensity yet your eye-brain
    system interprets the frequencies which strike
    your eye and the shirt is decoded as being
    "purple."

109
Color Addition
  • We have already learned that white is not a color
    at all, but rather the presence of all the
    frequencies of visible light the entire
    spectrum of visible light.
  • Combining the range of frequencies in the visible
    light spectrum is not the only means of producing
    white light.

110
  • White light can also be produced by combining
    only _______________ distinct frequencies of
    light, provided that they are widely separated on
    the visible light spectrum.
  • Any three colors (or frequencies) of light which
    produce white light when combined with the
    correct intensity are called _______________.

111
  • The most common set of primary colors is
  • _______________ (R)
  • _______________ (G)
  • _______________ (B)
  • When red, green and blue light are mixed or added
    together with the proper intensity, white (W)
    light is obtained.

112
  • Yellow (Y), magenta (M) and cyan (C) are
    sometimes referred to as _______________ colors
    of light since they are produced by the addition
    of equal intensities of two primary colors of
    light.

113
  • Any two colors of light which produce white are
    said to be _______________ colors of each other.
  • The complementary color of red light is cyan
    light. Since cyan light is the combination of
    blue and green light and blue and green light
    when added to red light will produce white light.
  • Thus, red light and cyan light (blue green)
    represent a pair of complementary colors they
    add together to produce white light.

114
Complementary Colors of Light
  • Red and Cyan
  • Green and Magenta
  • Blue and Yellow

115
Color Subtraction
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