Transcript Strand B: Energy

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
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 Transfer
Energy moves
from one
object to
another
without
changing form
versus
Energy Transformation
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.
Forms of Energy
Kinetic – the energy of an object’s motion (a falling rock)
Potential – stored energy due to an object’s position or shape
(a catapult)
Mechanical – the energy of an object’s 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 object’s 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)
Potential and Kinetic Energy
http://bishopcook09.wikis.birmingham.k
12.mi.us
Don’t 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
Elastic Potential
Energy
Potential Energy
Chemical PE
Gravitational
Potential
Energy
http://www.bbc.co.uk/schools/ks3bitesize/science/images/boulder.jpg
Gravitational Potential Energy
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)
Chemical Energy
http://i.ehow.co.uk/images/a04/bd/ic/chemical-energy-work-3.1800X800.jpg
Thermal Energy
http://energyboomer.typepad.com/.a/6a00d8345
1dceb69e200e553bcf40e8833-300wi
Electrical energy
converted to light
energy and thermal
energy
http://www.solar-pools.net/images/solarpool.jpg
Light/Radiant energy converted
to thermal energy
Sound, Electrical, and Nuclear Energy
http://www.physicscentral.c
om/experiment/physicsatho
me/images/drum.gif
Sound energy is produced
by vibrating matter
Stored potential
chemical energy
in the battery is
transformed into
electrical energy
when the circuit
is closed
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
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.
http://www.solpass.org/6-8Science/6s/Images/EnergyTransformations.gif
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.
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
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.
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.
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
Writing Response
Give an example of an energy conversion.
Make sure to discuss which forms of
energy are involved.
PARTICLES IN MOTION
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.
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
material’s volume when its temperature
decreases.
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.
http://www.photoanswers.co.uk/ImgGalleryTn/91/10191/2417_16333.jpg
Your Coke becomes cold because the heat from the soda
transfers into the ice, not the other way around.
Heat Transfer
Radiation

Heat transfer by radiation is the transfer
of heat through electromagnetic waves.

There is no direct contact between the
substances.
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.
Convection

Heat transfer by convection is the transfer
of thermal energy (heat) through the
fluid (liquids and gases) movement of
currents.
Convection

Warm fluids rise, cool down, sink, and
then are warmed again.
WRITING RESPONSE

Give example of conduction, convection,
and radiation from your everyday life.
Heat & Changes Of State

When thermal energy is added to solid ice,
its temperature increases until it starts to
melt, changing to liquid water.

When thermal energy is removed from
liquid water, it’s temperature decreases
until it starts to freeze, changing to solid
ice.

When thermal energy is added to liquid
water, its temperature increases until it
starts to vaporize, changing to a gas

When thermal energy is removed from a
gas, it changes to a liquid through a
process of condensation.

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.
Writing Response

What are two ways to change the state of
a substance?
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.
Conductors & Insulators

Thermal energy moves quickly in a
thermal conductor

Thermal energy moves slowly in a thermal
insulator
Writing Response

Indicate whether each object below is
either a conductor or and insulator:
A.
B.
C.
D.
Flannel shirtIron skilletCopper pipeOven mitt-
Writing Response

Indicate whether each object below is
wither a conductor or and insulator:
A.
B.
C.
D.
Flannel shirt- insulator
Iron skillet- conductor
Copper pipe-conductor
Oven mitt- insulator