Transcript of Learning Goals/Objectives 1.The students will define energy and describe and give an example of 9...
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- Learning Goals/Objectives 1.The students will define energy and
describe and give an example of 9 forms of energy 2.The students
will explain the Law of Conservation of Energy
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- What is Energy? Energy is the ability to do work on or cause a
change in matter The Law of Conservation of Energy Energy cannot be
created or destroyed, only transformed from one form to another
Energy Transferversus Energy Transformation Energy moves from one
object to another without changing form When one form of energy is
converted into another form of energy Work- the transfer of energy
that occurs when a force makes an object move in the direction of
the force; work is only being done while the force is acting on an
object.
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- Kinetic the energy of an objects motion (a falling rock)
Potential stored energy due to an objects position or shape (a
catapult) Mechanical the energy of an objects position and motion
(a pitched baseball) Chemical the energy stored in chemical bonds
(food, batteries) Thermal the energy due to the random motion of
atoms (cup of tea) Sound the energy due to an objects vibrations
(plucked guitar string) Electrical the energy of moving
electrons/an electric current (a hairdryer that is plugged into the
electrical socket) Light/Radiant the energy carried by
electromagnetic waves/vibrating electric charge (visible light,
infrared rays) Nuclear the energy stored in the nucleus of an atom
(stars) Forms of Energy
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- Potential and Kinetic Energy
http://bishopcook09.wikis.birmingham.k 12.mi.us Dont forget, there
is still potential energy at this point as well as thermal energy
and sound energy Kinetic energy is transformed into thermal energy
due to friction
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- Potential Energy
http://www.bbc.co.uk/schools/ks3bitesize/science/images/boulder.jpg
Chemical PE Elastic Potential Energy Gravitational Potential
Energy
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- The amount of GPE that an object has depends upon the mass of
the object and the height of the object above the ground. In each
scenario below, which of the objects has a greater potential
energy? (GPE = mgh)
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- Chemical Energy
http://i.ehow.co.uk/images/a04/bd/ic/chemical-energy-work-3.1-
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- Thermal Energy http://energyboomer.typepad.com/.a/6a00d8345
1dceb69e200e553bcf40e8833-300wi
http://www.solar-pools.net/images/solarpool.jpg Electrical energy
converted to light energy and thermal energy Light/Radiant energy
converted to thermal energy
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- Sound, Electrical, and Nuclear Energy
http://www.physicscentral.c om/experiment/physicsatho
me/images/drum.gif
http://www.solarsam.com/images/battery_circuit.JPG When the nuclei
of Uranium atoms are split (fission), lots of energy is released
heating water to steam to turn a turbine and generate electrical
energy Stored potential chemical energy in the battery is
transformed into electrical energy when the circuit is closed Sound
energy is produced by vibrating matter
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- Law of Conservation of Energy Energy cannot be created or
destroyed, only transformed from one form to another Potential
chemical energy (stored in the coal) is transformed into thermal
energy and then kinetic energy (spinning turbine) and then
electrical energy. The electrical energy powers your appliances,
computer, TV, hairdryer, etc. and is transformed into other forms
of energy such as mechanical energy, light energy, thermal energy,
sound energy.
http://www.solpass.org/6-8Science/6s/Images/EnergyTransformations.gif
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- Energy Transformations are never 100% efficient, because some
kinetic energy is always transformed into thermal energy or sound
energy and is unavailable for further useful work
http://www.ems.psu.edu/~radovic/efficiency.gif The light bulb
transforms electrical energy into light energy and thermal energy
Chemical energy transformed into mechanical energy, thermal energy,
and sound energy
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- Renewable Energy Resources Renewable energy resource- an energy
resource that is replaced as fast or faster than it is used Ex:
Solar- Converted into electric energy in solar cells(photovoltaic
cells) Sometimes transformed into thermal energy, which is used to
convert water into steam; the steam turns the generator, which
transforms mechanical energy into electric energy.
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- Wind- turbines use wind to turn a generator; changing kinetic
energy to electric energy. Hydroelectric- the mechanical energy of
falling water is channeled through a turbine and is transformed to
electric energy Geothermal- thermal energy from within the earth is
transferred to water, creating steam, which is used to turn
turbines in electric generators. Burning Biomass-includes wood,
plants, manure and garbage. Stored chemical energy is released and
transformed to electric energy.
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- Nonrenewable Energy Resources Nonrenewable energy resources-
energy resources that are available in limited amounts or are used
faster than they are replaced in nature Ex: Fossil fuels Petroleum
(oil) Natural gas Propane Coal Nuclear Energy
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- Writing Response Give an example of an energy conversion. Make
sure to discuss which forms of energy are involved.
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- PARTICLES IN MOTION
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- KINETIC MOLECULAR THEORY The transfer of thermal energy depends
on the movement of particles in the material. The Kinetic Molecular
Theory of matter explains how particles move. a)Particles make up
all matter b)Particles are in constant random motion c)Particles
constantly collide with each other and with the walls of their
container.
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- Temperature- the measure of the average kinetic energy of the
particles in a material. a)If particles in a material have little
kinetic energy, the material feels cold. b)SI Units- Kelvin (K) and
Celsius (C) Thermal Expansion - the increase in the Volume that a
material undergoes when its temperature increases. a.At higher
temperatures, particles move faster, requiring more volume because
they collide more often, pushing each other apart b.Thermal
contraction-the decrease in a materials volume when its temperature
decreases.
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- Kinetic energy is transferred from one material to another when
their particles collide. Heat is the movement of thermal energy
from one region of higher temperature to a region of lower
temperature Materials are said to be in thermal equilibrium when
the temperature of the materials that are touching are equal.
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- Your Coke becomes cold because the heat from the soda transfers
into the ice, not the other way around.
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- Heat Transfer
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- Radiation Heat transfer by radiation is the transfer of heat
through electromagnetic waves. There is no direct contact between
the substances.
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- Conduction The transfer of thermal energy by the collisions
between particles of matter. (through direct contact). Molecules
transfer energy to the molecules next to them.
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- Convection Heat transfer by convection is the transfer of
thermal energy (heat) through the fluid (liquids and gases)
movement of currents.
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- Convection Warm fluids rise, cool down, sink, and then are
warmed again.
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- WRITING RESPONSE Give example of conduction, convection, and
radiation from your everyday life.
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- Heat & Changes Of State When thermal energy is added to
solid ice, its temperature increases until it starts to melt,
changing to liquid water.
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- When thermal energy is removed from liquid water, its
temperature decreases until it starts to freeze, changing to solid
ice.
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- When thermal energy is added to liquid water, its temperature
increases until it starts to vaporize, changing to a gas
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- When thermal energy is removed from a gas, it changes to a
liquid through a process of condensation.
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- Sublimation occurs when a solid absorbs energy and changes
directly to a gas without becoming a liquid (ex: dry ice)
Deposition- when a gas changes directly to a solid without first
becoming a liquid.
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- Writing Response What are two ways to change the state of a
substance?
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- Writing Response What are two ways to change the state of a
substance? Two ways to change the state of a substance is by either
adding or removing thermal energy.
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- Conductors & Insulators Thermal energy moves quickly in a
thermal conductor Thermal energy moves slowly in a thermal
insulator
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- Writing Response Indicate whether each object below is either a
conductor or and insulator: A.Flannel shirt- B.Iron skillet-
C.Copper pipe- D.Oven mitt-
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- Writing Response Indicate whether each object below is wither a
conductor or and insulator: A.Flannel shirt- insulator B.Iron
skillet- conductor C.Copper pipe-conductor D.Oven mitt-
insulator