Download Energy - Pflugerville ISD

6th Grade Science
Fall 2005, Pflugerville ISD
© Fall 2005, Pflugerville ISD, 6th Grade
Unit 2: A World of Energy
Chapter 5:Energy and Energy
Resources
Section 1: What is Energy?
Section 2: Energy Conversions
Section 3: Using Energy
Section 4: Energy Resources
Fall 2005, Pflugerville ISD
What is Energy?
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
What Do You Think?
What is energy?
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Energy is the ability
to do work.
There are different
kinds of energy:
– Kinetic energy
– Potential energy
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Cite: http://www.nismat.org/ptcor/spondylo/gymnast.jpg
What is Energy?
Kinetic energy is the energy of motion
– All moving objects have kinetic energy
Kinetic energy depends on speed and mass
– The faster something is moving, the more kinetic
energy it has.
– The more massive a moving object is, the more
kinetic energy it has.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Potential energy is the energy an object has
because of its position or shape.
Lifting an object gives it gravitational potential
energy (GPE).
Gravitational potential energy (GPE)
depends on weight and height.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Energy comes in many forms:
– Thermal energy
– Chemical energy
– Electrical energy
– Sound energy
– Light energy
– Nuclear energy
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Cite: http://www.sirinet.net/~jgjohnso/formsofenergy.jpg
What is Energy?
Thermal energy is the total energy of the particles that make
up an object.
Because the particles are moving, they have kinetic energy.
– At higher temperatures, the particles move faster
– The faster particles move, the more kinetic energy they have and the
greater the object’s thermal energy is
Thermal energy also depends on the number of particles in a
substance.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Chemical energy is the energy stored in a
substance that can be released when the
substance reacts.
For example - when wood is burned, chemical
energy is released.
Another example - when you eat something,
your body is able to use the food’s chemical
energy.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Electrical energy is the energy of moving
electrons.
When you plug in your alarm clock and turn it
on, electrons in the wires move back and forth
(120 times per second).
As the electrons move, energy is transferred to
different parts of the clock to make it do work.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Cite: http://www.aplusenergy.com/images/electrictower.jpg
Cite: http://cache.corbis.com/agent/11/43/86/11438695.jpg
What is Energy?
Sound energy is caused by an object’s
vibrations.
When a guitar string vibrates, energy is
transferred from the moving string to the air
particles around it.
The particles transfer energy from one another
and finally cause your eardrum to vibrate, and you
hear the sound of the guitar.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Light energy is caused by the vibrations of
electrically charged particles.
The vibrations that transmit light energy do not
require particles to transmit energy.
Light energy, unlike sound energy, can be
transmitted through a vacuum (like space).
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Nuclear energy is caused by changes in the
nucleus of an atom.
Nuclear energy is produced two ways:
– When two or more nuclei join together (nuclear
fusion)
– When the nucleus of an atom splits apart
(nuclear fission)
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Types of Energy Review- Click
here to review the types of energy.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
What is Energy?
Activity
Make a simple drum. What do you
hear? Change the way you hit the
drum. What happens to the
sound?
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
See speaker notes for lab.
Pre-AP Extension
Electric current is the flow of
electrons form an object that has
many electrons to another object
that has too few electrons.
Explore circuits with a battery,
wires, light bulbs, and a voltmeter.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
See speaker notes for lab.
Let’s Review
1. What is Energy?
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Answer
Energy is the ability to do work.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Let’s Review
2. How are energy and work
related?
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Answer
Energy is the ability to do work
and work cannot be done without
energy.
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Let’s Review
3. What are the different forms of
energy?
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Answer
Thermal
Chemical
Electrical
Sound
Light
Nuclear
Chapter 5 Section 1
Fall 2005, Pflugerville ISD
Energy Conversions
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
What Do You Think?
How is a moving pendulum
converting potential energy to
kinetic energy?
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
An energy conversion is a change from
one form of energy to another.
Any form of energy can be changed into
any other form of energy.
→
Chemical Energy
Chapter 5 Section 2
Kinetic Energy
Fall 2005, Pflugerville ISD
Energy Conversions
Mechanical energy is the sum of an
object’s kinetic and potential energy.
Example:
– When a pendulum is lifted, potential energy is
stored.
– When the pendulum swings, the potential
energy is changed to kinetic energy.
– The total energy is the pendulum’s mechanical
energy.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
When you eat, the chemical energy of
the food is converted by your body to other
forms of energy.
Can you think of ways your body uses
chemical energy?
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
Activity
Take a close look at the energy
conversion that occurs as a
pendulum swings.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
See speaker notes for lab.
Energy Conversions
Energy
conversions also
occurs in plants.
Plants use
chlorophyll to
convert light
energy to
chemical energy.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Cite:http://www.cneccc.edu.hk/subjects/bio/album/Chapter8/images/PHOTOSYNTHESIS0.jpg
Energy Conversions
Machines convert electrical energy into
other forms of energy.
What types of energy does a hair dryer
convert electrical energy into?
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
The Law of Conservation of Energy
states energy can neither be created nor
destroyed.
The total amount of energy in a closed
system is always the same.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
Friction is a force that opposes motion
between two surfaces that are touching.
Some energy that appears to be “lost”
actually becomes thermal energy due to
friction.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Cite: http://www.abc.net.au/juniors/pages/2000/transport/land/img/friction.jpg
Energy Conversions
Energy efficiency compares the amount
of energy before a conversion with the
amount of useful energy after the
conversion.
The less energy that must be used to
overcome friction, the more efficient the
energy conversion.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
What do we call cars that move
through the air more easily and use
less energy to overcome friction?
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
A perpetual motion machine is a machine that
runs forever without any added energy – 100%
efficient.
Because all energy conversions result in some
form of energy that isn’t useful, perpetual motion
is impossible.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Cite: http://www.w-uh.com/images/perpetual_wheel.gif
Energy Conversion
View some examples of energy
conversions by clicking here.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Energy Conversions
Activity
Design a protection system for an
egg so you can drop it without it
breaking thus the energy transfer
will go into your protection system
and not the shell.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
See speaker notes for lab.
Pre-AP Extension
Explore the different forms of
energy associated with different
object and mechanisms and how
they convert energy from one
form to another.
See speaker notes for lab.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Let’s Review
1. Identify three energy
transformations occurring during
the production of energy for
human use.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Answer
Sample answer: A battery
converts chemical energy into
electrical energy.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Let’s Review
2. Describe the energy conversions
that take place when you ride in a
car.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Answer
Sample answer: The car converts
the chemical energy from
gasoline into thermal energy;
which is then used to do work on
the pistons. This gives the car
kinetic energy.
Chapter 5 Section 2
Fall 2005, Pflugerville ISD
Using Energy
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Using Energy
What Do You Think?
How is energy transferred
when you are riding a bike?
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Using Energy
A machine is a device that can make work
easier by changing the direction or size of
force needed to do work.
Machines cannot transfer or change more
energy than you transfer to them.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Using Energy
When machines transfer energy, they can
also convert energy.
Your alarm clock is an example: It transfers
electrical energy to sound energy to help you
wake up in the morning.
What are some other examples of machines
causing energy conversions?
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Using Energy
Heating systems move thermal energy to
cooler areas.
Air or water is used to move thermal energy
from burning fuel to other areas of a house
or building.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Using Energy
Solar heating systems convert light energy from the
sun into thermal energy.
Active solar heating systems have moving parts –
machines that move the sun’s energy throughout a
building (such as pipes, fans, and storage tanks for
water to be heated).
Passive solar heating systems do not have moving
parts – they use thick walls and large windows that
face south.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Using Energy
Cooling systems move thermal energy out
of the area that is to be cooled.
To move thermal energy from a cool area
(indoors) to a warm area (outdoors), a
cooling system must do work.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Cite: http://img.epinions.com/images/opti/8c/48/Amana_Touch_Cooling_Series_Room_Air_Conditioner_Model_AAC081STA-resized200.jpg
Using Energy
Most cooling systems use electrical
energy to do the work of cooling.
A machine called a compressor does the
work of compressing a refrigerant.
A refrigerant is a gas that can easily
change state to become liquid.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Using Energy
Activity
Have a guest speaker come in
such as an air conditioning expert
to talk to the kids about
refrigerators and heating systems.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Let’s Review
1. What is the role of machines in
energy transfer?
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Answer
Machines can transfer energy
from one object to another as
they make work easier.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Let’s Review
2. Compare the hot-water heating
system and an active solar
heating system.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Answer
Both systems use pumps to move
heated water throughout the house.
The thermal energy used to heat the
water comes from burning fuel in a
hot-water system and from the sun in
an active solar heating system.
Chapter 5 Section 3
Fall 2005, Pflugerville ISD
Energy Resources
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
What Do You Think?
What are some of the energy
resources we use everyday?
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
An energy resource is a natural resource
that people can turn into other forms of
energy in order to do useful work.
Nonrenewable resources cannot be
replaced after they are used or can only
be replaced over thousands or millions of
years.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
Fossil Fuels such as coal, petroleum, and
natural gas formed from the buried
remains of plants and animals that lived
millions of years ago.
The stored energy of these remains is
released when the fossil fuels are burned.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
Coal – most coal in the U.S. is burned in
power plants to generate electrical energy.
Petroleum – gasoline, kerosene, wax, and
other petrochemicals come from
petroleum.
Natural Gas – the cleanest burning fossil
fuel is used in heating systems, stoves
and ovens, and a few vehicles.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
1. The chemical energy of the fossil fuel is
turned to thermal energy by burning.
2. Thermal energy is used to boil water and
change it to steam.
3. Thermal energy is changed to
mechanical energy as steam pushes
against the blades of a turbine.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
4. An electric generator changes
mechanical energy into electrical energy.
5. The electrical energy can be sent to
homes and businesses through electrical
wires.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Cite: http://newsimg.bbc.co.uk/media/images/39132000/jpg/_39132217_electricity_203.jpg
Energy Resources
Nuclear power plants also generate thermal
energy that boils water to produce steam.
Nuclear energy is generated from radioactive
elements such as uranium.
In a nuclear power plant, a special process splits
the nucleus of a uranium atom in two – giving off
nuclear energy.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
Renewable energy resources can be
used and replaced in nature over a short
period of time.
– Solar Energy
– Energy from water
– Wind energy
– Geothermal energy
– Biomass
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
Solar Energy – sunlight can be changed into
electrical energy by solar cells.
Energy from water – the potential energy of
water in a reservoir can be changed into kinetic
energy as the water flows downhill through a
dam. The kinetic energy of the falling water
turns turbines, which change it to electrical
energy by turning a generator.
Wind Energy – the kinetic energy of wind can
turn the blades of a windmill. A wind turbine
changes the kinetic energy of the air into
electrical energy by turning a generator.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
Geothermal energy – Thermal energy
caused by the heating of Earth’s crust is
used by pumping water underground into
areas of hot rock. The water returns to the
surface as steam – which can then be
used to turn a generator to change
mechanical energy into electrical energy.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Energy Resources
Geothermal heating and cooling.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Cite: http://www.rlcave.com/cooling%20_animation.gif
Energy Resources
Biomass – plants use an store energy from the
sun. Organic matter that can be burned to
release energy is called biomass. Some plants
can be turned into liquid fuel - for example, corn
can be used to make ethanol.
Cite: http://cr.middlebury.edu/es/altenergylife/biomass!!.jpg
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Cite: http://www.caribbeanedu.com/images/kewl/biomass01.gif
Energy Resources
1. 100 tons of plant matter (the amount that
exists in 40 acres of wheat)
2. Burning that gallon puts 20 lbs. of CO2 into the
air.
3. The U.S. consumes 131 billion gallons of gas
annually = 25 quadrillion lbs. of biomass =
putting 26 trillion lbs. of CO2 into the air.
4. Since 1751, humans have burned the amount
of fossil fuels that would have come from all
the plants on Earth for 13,300 years.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Pre-AP Extension
Nonrenewable resources will exhaust over
time. Conservation is a way of using less
energy along with the increase use of
renewable resources. Explore the deletion
of fossil fuel and the need to conserve and
develop renewable resources.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
See speaker notes for lab.
Let’s Review
1. Describe fossil fuels and
biomass from their source to their
use.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Answer
Fossil fuels are formed from the
remains of plants and animals that
lived millions of years ago, and
biomass is organic matter that is
obtained from things living today.
Both are burned to released chemical
energy, which can be converted into
other forms of energy.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Let’s Review
2. Determine whether the following
energy types are renewable,
nonrenewable, or inexhaustible:
–Nuclear energy
–Solar energy
–Biomass
Chapter 5 Section 4
Fall 2005, Pflugerville ISD
Answer
Nuclear energy is nonrenewable.
Solar energy is inexhaustible.
Biomass is renewable.
Chapter 5 Section 4
Fall 2005, Pflugerville ISD