Energy

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Energy
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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

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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

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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

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Forms of Energy
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Types (conditions) of energy

• Kinetic energy energy that is actively doing
  something
• Potential energy stored energy that is waiting
  to be used

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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

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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

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Mechanical Energy
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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

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Electrical Energy
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Chemical Energy

• Energy of chemical bonds
• Released when chemical bonds are broken
• Explosions
• Burning wood
• Energy in candy bar

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Chemical energy
oxygen
Bond (Energy stored in bond)
Water produced
Bond (Energy stored in bond)
Energy release
Hydrogen
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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

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• Simulation of heating of gases

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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

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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

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Energy Transformation and Transfer
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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

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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

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• 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

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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

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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

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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

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Three Forms of Heat Transfer
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Conduction

• Solid objects in direct contact with each
  transfer heat by conduction transfer

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Convection

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

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Radiation

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

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Work, Force and Simple Machines
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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

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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

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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

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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

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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

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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

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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

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Which machine is easier to use
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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

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• 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

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Electricity and Magnetism
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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

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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
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Electrical Current
Free Electron
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Electric current is the movement of electrons
down a conductor
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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

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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

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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

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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)

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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?

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Oersteds Discovery
Electric current from a battery causes a magnetic
field around the wire
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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

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Faradays Discovery
Movement of a magnet toward a coil of wire causes
electric current in the wire
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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

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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

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Electrical Generator
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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

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How generators make electricity
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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

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

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Electromagnet
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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

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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

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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.

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Series Circuit

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

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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

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Parallel Circuit

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

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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