Download Energy Lesson

Who’s doing work?
Work is only done by a force on an
object if the force causes the object
to move in the direction of the force.
Objects that are at rest may
have many forces acting on them,
but no work is done
if there is no movement.
Work,
the product of the force exerted on
an object and the distance the object
moves in the direction of the force.
W = F·d
Power,
by definition, is
the time rate of doing work;
or the time rate transfer of energy.
P=W/t
Power,
My friend,
has been so stressed.
His boss keeps
making him
work over time.
P=W/t
Energy
click on energy for a short video
Energy:
Forms and
Changes
Nature of Energy
• Energy is all around you!
– You can hear energy as sound.
– You can see energy as light.
– And you can feel it as wind.
Nature of Energy
• You use energy when
you:
– hit a softball.
– lift your book bag.
– compress a spring.
Nature of Energy
Living organisms need energy for
growth and movement.
Nature of Energy
• Energy is involved
when:
–
–
–
–
a bird flies.
a bomb explodes.
rain falls from the sky.
electricity flows in a
wire.
Energy
the ability to do work
Energy comes in many forms:
mechanical, electrical , magnetic, solar,
thermal, chemical, etc...
The SI unit of energy is the Joule.
Energy
Energy
Potential Energy
Stored energy and the
energy of position
Kinetic Energy
Motion of waves,
electrons, atoms,
molecules, and
substances
Potential Energy
Stored energy and the
energy of position
Chemical Energy
Energy stored in the bonds of
atoms and molecules
Nuclear Energy
Energy stored in the nucleus of
an atom – the energy that holds
the nucleus together
Potential Energy
Stored energy and the
energy of position
Gravitational
Energy
Energy of place or position
Elastic Energy
Energy stored in objects by the
application of force.
Kinetic
Energy
Motion of waves,
electrons, atoms,
molecules, and
substances
Radiant Energy
Thermal Energy
Electromagnetic energy that
travels in transverse waves
Internal energy in substances –
vibration or movement of atoms and
molecules in substances
a.k.a. “heat”
Kinetic
Energy
Sound
Energy
Movement of
energy through
substances in
longitudinal
waves
Motion of waves,
electrons, atoms,
molecules, and
substances
Mechanical
Motion
Movement of substance
from one place to another
Electrical
Energy
Movement of
electrons
Potential Energy
Stored Energy
gravitational potential energy
GPE = mgh
m - mass of object in kg
g - acceleration of gravity in m/s2
h - height of object, in m
GPE – gravitational potential energy in J
Kinetic Energy
energy of motion
All moving objects that
have mass have kinetic energy.
KE = 1/2
2
mv
m - mass of the object in kg
v - speed of the object in m/s
KE - the kinetic energy in J
Different
Types of
Energy.
Kinetic Energy
Anything that moves has kinetic energy.
Gravitational Potential Energy (GPE)
Anything above the ground has gravitational
potential energy i.e. anything that can fall,
like ski jumpers, aeroplanes and climbers.
Nuclear Energy
Released only from nuclear
reactions
The sun and all of the stars.
Hydrogen bomb (Fusion)
Nuclear power plants
Sound Energy
Anything noisy gives off sound energy like vocal chords,
speakers and instruments.
Chemical Energy
Anything with stored energy which can be
released by a chemical reaction has
chemical energy, things like food fuels and
batteries.
Radiant Energy
also called electromagnetic energy
All life on Earth depends upon radiant energy from the
sun
Examples: radio waves, microwaves, Xrays,
Heat/Thermal Energy
Anything with a temperature
above absolute zero (-273°C) has
heat energy. That means
everything has some thermal
energy.
Light Energy
Anything luminous gives off light energy, like the
sun, light bulbs , candles and glow worms.
Electrical Energy
Electrical energy is very useful, because its easily
converted into other forms – wherever there's a current
flowing there's electrical energy.
Elastic Energy
Anything stretched, has elastic energy – things like
rubber bands, springs, knickers, elastic etc
Different types of energy
click on link above for a video
:
thermal
light
sound
elastic
gravitational
kinetic
electrical
chemical
nuclear
Can you think of
examples of each
type of energy?
Energy transfer
Energy can be changed from one form to another.
For example:
 Chemical energy in food is
converted to thermal energy
and kinetic energy by our bodies.
 Gravitational energy in a ball is
converted to kinetic energy
when it falls to the ground.
What other energy transfers can you think of?
Energy
the ability to do work
Energy comes in many forms:
mechanical, electrical , magnetic, solar,
thermal, chemical, etc...
The SI unit of energy is the Joule.
Energy
Energy
Potential Energy
Stored energy and the
energy of position
Kinetic Energy
Motion of waves,
electrons, atoms,
molecules, and
substances
Potential Energy
Stored energy and the
energy of position
Chemical Energy
Energy stored in the bonds of
atoms and molecules
Nuclear Energy
Energy stored in the nucleus of
an atom – the energy that holds
the nucleus together
Potential Energy
Stored energy and the
energy of position
Gravitational
Energy
Energy of place or position
Elastic Energy
Energy stored in objects by the
application of force.
Kinetic
Energy
Motion of waves,
electrons, atoms,
molecules, and
substances
Radiant Energy
Thermal Energy
Electromagnetic energy that
travels in transverse waves
Internal energy in substances –
vibration or movement of atoms and
molecules in substances
a.k.a. “heat”
Kinetic
Energy
Sound
Energy
Movement of
energy through
substances in
longitudinal
waves
Motion of waves,
electrons, atoms,
molecules, and
substances
Mechanical
Motion
Movement of substance
from one place to another
Electrical
Energy
Movement of
electrons
What impacts an object’s GPE?
Who has
more
energy?
Who has
more
energy?
Potential Energy
Stored Energy
gravitational potential energy
GPE = Wh
W – Weight of object in N
h - height of object, in m,
GPE – gravitational potential energy in J
Roller Coaster Conversions
The NEED Project
Law of Conservation of Energy
“Energy can be neither created nor destroyed.
It may only change forms.”
energy before the event = energy after the event
Examples:
•A dropped object loses gravitational PE as it gains KE.
•A block slides across the floor and comes to a stop.
•A compressed spring shoots a ball into the air.
Law of Conservation of Energy
Watch the video and take notes on the
law of conservation of energy
Turning on the Light in Your Closet
Thermal
Sound
Radiant
Motion
Describe energy transfer in each device
 burning match
 portable torch
 microphone
 radio
 television
 catapult
 mobile phone
 car
Describe energy transfer in each device
 burning match
microphone
 radio
 television
 car
chemical to thermal and light
sound to electrical
electrical to sound and thermal
electrical to sound and light and thermal
chemical to kinetic and sound and thermal
In all these transfers the energy is not lost, it is conserved.
Energy cannot be destroyed or created.
Energy poker
Look at the scenes on the slides that follow.
Make a bid for the number of energy transfers
that you can see. The person with the highest bid
has to explain where they are. If they fail to find
that number they lose.
Can you win at energy poker?
Let’s look at an example first…
First Example…
Energy poker score: 1
Sunlight energy converted into heat to boil the water for tea