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Energy

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Title: Energy


1
Energy
2
What is energy
  • Energy is the action or stored ability to cause
    change in matter through movement, temperature or
    state of matter
  • It is also the ability to create work
  • It is not a substance like matter, but rather an
    unseen force that is present in the universe

3
What does energy do
  • Energy moves things
  • Energy lights things
  • Energy heats things
  • Energy changes things into other things
  • Energy can not be created or destroyed, but it
    can change its form

4
Where does energy come from
  • Energy can not be created or destroyed, but it
    can change from one form to another
  • This is know as the Law of Conservation of Energy
    (Newtons First Law of Thermodynamics

5
Forms of Energy
6
Types (conditions) of energy
  • Kinetic energy energy that is actively doing
    something
  • Potential energy stored energy that is waiting
    to be used

7
There are seven forms of energy
  • Mechanical energy of movement
  • Electrical energy of electric charges
  • Chemical energy of chemical compounds
  • Heat energy in an object
  • Nuclear energy inside an atom
  • Solar energy of the sun
  • Sound the energy of vibration

8
Mechanical Energy
  • Energy of motion and position
  • If not moving, an object has potential mechanical
    energy
  • car parked on a hill
  • If moving, an object has kinetic mechanical
    energy
  • car rolling down a hill

9
Mechanical Energy
10
Electrical Energy
  • Energy of electrical charges
  • Electrical energy in a conductor -current
    electricity
  • House wiring
  • Electrical energy not in a conductor- static
    electricity
  • Doorknob spark
  • Lightning

11
Electrical Energy
12
Chemical Energy
  • Energy of chemical bonds
  • Released when chemical bonds are broken
  • Explosions
  • Burning wood
  • Energy in candy bar

13
Chemical energy
oxygen
Bond (Energy stored in bond)
Water produced
Bond (Energy stored in bond)
Energy release
Hydrogen
14
Heat (Thermal) Energy
  • Energy of moving atoms in an object
  • More movement - more energy
  • More energy - more movement
  • Large objects have more energy than small objects
    if temperature is same
  • Temperature is average heat energy

15
  • Simulation of heating of gases

16
Nuclear Energy
  • Energy stored in nucleus of atoms
  • Holds atomic particulars together
  • Tremendous release of energy if atom is split
  • Atomic bomb
  • Nuclear power plants

17
Solar Energy
  • Energy from solar radiation
  • Largest source of energy on earth
  • Many other energy sources come from solar energy
  • Wind power
  • Fossil fuels
  • Biomass fuel
  • Provides most of heat and light on earth

18
Energy Transformation and Transfer
19
Energy Transformations
  • Energy changes from form to form
  • Electricity is generated by mechanical energy
    (generators) that are turned by other forms of
    energy
  • Heat - steam from
  • sun (Solar)
  • burning fuels (Chemical)
  • fission reactions (Nuclear)
  • Mechanical moving water or wind

20
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21
Electricity can be transformed easily
  • Electricity can be transformed into many other
    forms of energy
  • Light energy light bulbs
  • Sound energy radios
  • Chemical energy battery charger
  • Mechanical energy electric motor
  • Heat energy toaster

22
  • Not all energy is transformed
  • Some is lost as heat or friction
  • Efficiency is a measure of how much energy is
    transferred in percent
  • Examples
  • Chemical to mechanical (engine, your body) loses
    heat
  • Electrical to mechanical (motor) loses to
    friction
  • High efficiency little energy lost

23
Energy can be stored
  • Energy can be stored for use
  • Mechanical energy can be stored as elastic or
    gravitational potential
  • Electrical energy can be stored as chemical
    potential in a battery
  • Plants store chemical energy through
    photosynthesis
  • Chemical energy is stored in explosives

24
The Law of Conservation of Energy
  • Energy is never lost even with low efficiency
  • All energy is conserved in one form or another
  • The Law of Conservation of Energy states Energy
    is not created or destroyed, it only changes forms

25
Energy can be transferred
  • Energy can be moved (transferred) from one object
    to another
  • Mechanical legs using motion move bicycle
    pedals which give motion to the wheels
  • Heat moving atoms bump into each other and
    transfer movement from one to another

26
Three Forms of Heat Transfer
27
Conduction
  • Solid objects in direct contact with each
    transfer heat by conduction transfer

28
Convection
  • Gases and liquids transfer heat away from the
    source by convection transfer

29
Radiation
  • Energy traveling by waves through empty space
    transfer heat radiation transfer

30
Work, Force and Simple Machines
31
What is Work
  • Anytime some object is moved some distance, work
    is accomplishedif
  • A force is required to move that object that
    distance
  • A force is a push or a pull in one direction
  • Energy is required to create that force
  • Therefore, another definition of energy is
  • Energy is the ability to do work

32
What is Work
  • No matter how much effort is applied, if there is
    no movement, there is no work
  • There is also a requirement that the movement is
    because of the effort
  • Therefore, the force must be in the direction of
    the movement
  • Even if there is force applied, if it is not in
    the same direction as the movement, no work is
    done

33
Examples
  • Trying to unscrew a lid that wont open
  • No work is done
  • Carrying a bag a groceries in your arms
  • No work is done
  • Picking up a feather
  • Work done
  • Pushing a ant across a piece of paper
  • Work done

34
The formula for work
  • The is an easy formula to find out how much work
    is being done
  • Work is equal to the amount of force being used
    multiplied by the distance the object is moved
  • Work Force x distance

35
What are simple machines
  • Simple machines are devices that allow work to
    spread out over a longer distance in exchange for
    a smaller force
  • Because work is equal to force x distance, a
    longer distance multiplied by a smaller force
    will mean the same amount of work is done
  • Or a bigger force multiplied by a shorter
    distance will mean the same amount of work is done

36
How do simple machines work
  • By using a machine that moves a long distance,
    the force needed to do work will be less
  • A large wheel turns a greater distance by is
    easier to turn than a smaller wheel if both are
    attached to the same load
  • A lever with a long arm is easier to push or pull
    than one with a short arm is they both are
    pushing the same load

37
More Examples
  • A screw with more turns on it is easier to screw
    in than one with less turns, even though it takes
    longer to screw in
  • A pulley that uses more rope is easier to pull up
    than one that only uses a small amount of rope
  • A long ramp is easier to walk up than a short one
    even though it takes more steps to do it

38
Which machine is easier to use
39
Vocabulary
  • Work the force required to move an object some
    distance
  • Lever a beam or rod that rotates around a fixed
    point called a fulcrum
  • Arm the beam or rod of a lever
  • Fulcrum fixed point that a lever turns around
  • Wheel and axel a large wheel that is attached
    to a smaller wheel by a rod

40
  • Pulley a kind of wheel that has a groove hold a
    rope of cord that passes over or under the wheel
  • Inclined plane a slanted surface
  • Wedge a moveable inclined plane, also sometimes
    two inclined planes placed together
  • Screw an inclined surface that has been wrapped
    around a cylinder

41
Electricity and Magnetism
42
Electricity and Magnetism are caused by the same
thing
  • Both electricity and magnetism have the same
    beginningmovement of electrons
  • Electrons are small particles that spin or fly
    around the nucleus of an atom
  • In magnetism the direction of spin sets up a
    field of energy around the atom called a magnetic
    field
  • In electricity, free electrons moving along a
    conductor causes electric current

43
Magnetism
North pole Magnetic Domain
South Pole
When the atoms all point in the same direction, a
magnetic field is produced called a domain which
has a north pole and a south pole
44
Electrical Current
Free Electron
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Electric current is the movement of electrons
down a conductor
45
Magnetism
  • Only three elements from the periodic table of
    elements are capable of producing magnetic
    fieldsiron, nickel and cobalt
  • These are known as the ferrous metals from the
    Latin work for ironferris
  • When a large enough number of atoms of these
    metals are lined up into a domain, the piece of
    metal is known as a magnet

46
Magnets
  • Magnets have a magnetic field around them that
    has a north pole and a south pole, just like the
    domain around atoms
  • Magnetic energy leaves the south pole of a magnet
    and circles around and enters the north pole of
    that magnet

47
Magnetic Attraction
  • Because magnetic energy leaves a north pole and
    enters a south pole, magnets act strangely around
    other magnets
  • A north pole of one magnet will be attracted to
    the south pole of another magnet
  • A north pole of one magnet will be repelled by a
    north pole of another magnet
  • Opposites attract, likes repel is the rule

48
The Earth is a Magnet
  • Because of its very large iron-nickel core, the
    earth acts like a very large magnet
  • The spinning of the liquid core sets up a
    magnetic field around the earth with a magnetic
    north pole and south pole
  • A compass reacts to the magnetic field of the
    earth because it too is a magnet
  • The south pole of the earth attracts the south
    pole of a compass because the south pole of a
    compass is really a north pole of another magnet
    (the needle of a compass is a magnet)

49
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50
Whats this got to do with electricity
  • In the early 1800s a Swedish scientist named
    Hans Oersted discovered that moving electricity
    through a wire that had compass near it made the
    compass swing
  • Something in the wire had changed
  • A magnetic field had been produced in the wire
    but by what?
  • He discovered that electrons moving through a
    wire produce a magnetic field
  • Coolbut so what, what good was it?

51
Oersteds Discovery
Electric current from a battery causes a magnetic
field around the wire
52
Magnetism has everything to do with electricity
  • A short time later an English scientist named
    Michael Faraday discovered just the opposite
  • He found that moving a magnet through a coil of
    wire caused an electric instrument to move
  • Somehow the movement of a magnet caused electrons
    to leave their atoms and travel to other
    atomselectric current

53
Faradays Discovery
Movement of a magnet toward a coil of wire causes
electric current in the wire
54
A new beginning for energy
  • Faradays discovery led to the invention of both
    the electric motor the electric generator
  • A motor is a device that can use electricity to
    produce mechanical energy
  • A generator is a device that uses mechanical
    energy to produce useable amounts of electrical
    energy

55
Electricity generators
  • Because of Faradays discovery, it is possible to
    create large amounts of electricity
  • Generators are devices that contain a magnet that
    rotates within a coil of wire
  • The movement of the magnet causes electrons to
    begin to move within the wire
  • That movement of electrons is electricity

56
Electrical Generator
57
Electricity Production
  • By connecting a generator to a power source,
    electricity can produced
  • Wind power, hydro electrical power, fossil fuel,
    and nuclear energy can provide the energy to
    create electricity
  • Water is heated to steam by the above energy
    sources
  • The steam turns a turbine that drives the
    generator

58
How generators make electricity
59
Electric Motors
  • Electric motors are similar to generators, but
    they have one major difference
  • Generators use mechanical energy to turn a magnet
    inside a coil of wire
  • Generators use magnetism to create electricity
  • Motors use electrical energy in a coil of wire to
    create a magnetic field which turns a magnet
    connected to the drive shaft of the motor
  • Motors use electricity to create magnetism

60
Electric motor
Electric energy flows from a power source through
the loop and back to the power source
_

61
Electromagnets
  • Magnetism created by electricity has some
    advantages over permanent or natural magnets
  • Electromagnets consists of a coil of wire, a
    power source, and a piece of ferromagnetic
    material (iron, nickel or cobalt)
  • Electromagnets can be controlled they can be
    turned on and off
  • This allows them to be used in devices such as
    door bells, telephones and junk yard cranes

62
Electromagnet
63
Electric Circuits
  • When electricity is generated, it is sent to do
    work
  • The pathway that the electricity follows is
    called a circuit
  • Electricity must always return to its source or
    into the ground or it will not flow
  • Circuits have four parts power source,
    conductor, device, and a switch (optional)
  • There are two different types of circuits series
    circuits and parallel circuits

64
Electric Circuits
  • In an electric circuit, the pathway must be
    complete from the source back to the source to
    allow electricity to move through the circuit

65
Series Circuit
  • If electricity follows a single pathway from the
    source through all of the parts and then back to
    the source it is called a series circuit.

66
Series Circuit
  • If any part of a series circuit stops working,
    the entire circuit stops working

67
Parallel Circuit
  • If electricity has more than one pathway that it
    can follow from the source through all the parts
    it is called a parallel circuit

68
Parallel Circuit
  • If any part of the circuit stops working, the
    rest of the circuit will continue to work

69
Electricity can be transformed into many other
types of energy
  • Electricity can be used to
  • toaster or room heat
  • Electricity can be used to create light as in a
  • lamp
  • Electricity can be used to create motion as in a
  • motor
  • Electricity can be used to create sound as in a
  • radio or doorbell
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