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Energy
Energy Vocabulary
•energy
•kinetic Energy
•potential Energy
•gravitational potential
energy
•elastic potential energy
•mechanical energy
•joule
•mass
•heat
•law (scientific law)
•Law of Conservation
of Energy
•energy
tranformation
Where does the energy come
from?
• Atoms!!!
• EVERYTHING and ANYTHING has atoms,
molecules, and particles in it.
• The ENTIRE UNIVERSE is made of atoms
• These atoms are constantly moving and
interacting with each other. This
movement allows energy to transfer
between atoms.
Proof that atoms exist and
they can be moving:
DEMO: Dry Ice
•
•
•
•
Are these scissors alive?
Does it have atoms?
Are they moving?
When atoms change temperature they either
expand or contract.
• When they expand they gain energy and when
they contract they loose energy, lets observe
what happens to different items in dry ice.
A little bit of history
• The theory of energy was made law in the 19th
century when scientists were able to prove that any
form of energy can be transformed into another
form, but the total energy always remains the
same.
• A theory is an idea that has not been fully proven
by science
• A law has been proven beyond any reasonable
doubt and can be repeated and repeated with the
same outcome.
Energy
• Energy occurs in many forms and has the ability
to cause change.
• Therefore, we must remember the Law of
Conservation of Energy, that states: Energy can
never be created nor destroyed, it can only be
changed (transferred)!
• This process can be witnessed in the following
energy transformation of a light bulb:
Electrical
Energy
Light Energy
Heat Energy
How is energy transferred?
• When two substances touch or interact they
share energy. One object gains energy and
the other transfers it out. In BOTH objects
the mass remains the same as only the
energy is transferred.
– Ex. 4 student dominoes line up
– Ex. Electrostatic generator
Kinetic and Potential Energy
• Energy that is due to motion is kinetic energy,
and energy that is stored and has the ability to
move, but is not moving is potential energy.
• Kinetic energy depends on an objects speed and
mass. The faster an object moves, the more
kinetic energy it has. The greater the mass, the
greater the kinetic energy.
• If objects collide then the kinetic energy can be
transferred from one object to another.
What Is Energy?
Kinetic
Energy
The kinetic
energy of an
object
depends on its
speed and
mass.
Using SI Units to measure
Energy
Quantity
SI Unit
Force
Newton
Height
Meter
Work
Joule
Mass
Kilogram
Energy
Joule
Can We measure kinetic
energy?
• Yes!! We can measure kinetic energy in
Joules using the following formula:
Kinetic energy = ½ X Mass X Speed2
Let’s try:
– Energy of a person running 5m/s with a mass of
70kg
– Energy of a cat jumping around at 2 m/s with a
mass of 18 Kg
– *More practice on pg. 293
Can We measure potential
energy?
• Yes!! We can measure potential energy in
Joules using the following formula:
Gravitation P= Weight X Height
Let’s try:
– Energy of a person has a height of 5dm with a
weight of 70kg
– Energy of a cat jumping around 2 dm tall with a
weight of 18 Kg
– More practice on pg. 294
What Is Energy?
Gravitational
Potential
Energy
The rock
climbers have
gravitational
potential energy,
which is
potential energy
related to an
object's height.
What Is Energy?
Elastic Potential Energy
The energy stored in a stretched object, such as the
trampoline, is elastic potential energy. Rank the
amount of elastic potential energy of the trampoline
from greatest to least.
Using Mechanical Energy
• An object’s mechanical energy is a
combination of its potential energy and both
potential energy and kinetic energy.
Mechanical Energy = Potential Energy + Kinetic Energy
*Practice on page 297
Conservation of Energy
Pendulum
A continuous
transformation
between
potential and
kinetic energy
occurs in a
pendulum. What
are the types of
energy the
pendulum has at
positions A, B,
and C?
Conservation of Energy
Conserving Energy While You Ride
Transformations between potential and kinetic
energy occur during a roller coaster ride. How much
potential and kinetic energy does the coaster have at
each point?
Let’s try a real life demo!
Thermal Energy Review
• Since kinetic energy is measured by the
movement of molecules, this is also how we
can measure temperature, as the more
kinetic energy it has, the higher the
temperature will be.
• We can measure this with a thermometer, by
measuring the movement of the molecules
either expanding or contracting.
Thermal Energy (cont.)
• Heat and thermal energy move the same as
the energy from a substance moves from
higher temperatures (warmer) to lower
temperatures (colder).
– Burning fossil fuels produces thermal energy that is used
to boil water and produce steam
– Thermal Energy can transfer heat in three ways:
conduction, radiation, and convection.
– Can you remember what each transfer of Thermal
Energy involves and give an example of each?
Using Nuclear
and Chemical Energy
• Nuclear energy is stored chemical energy.
– Ex: The Sun
• Chemical energy can come from any of the
following:
– Food
– Muscle Use
• Any other uses you could think of?
Using Radiant Energy
• Radiant energy is from any form of radiation.
– A Sun tan - the Sun is transferred into chemical
energy on your skin and can get you darker
– Visible light produces energy you can see
– Radiant energy can also be transferred into
electrical energy(X-rays, gamma rays)
Using Electrical Energy
• One of the most useful forms of energy
– Electrical is converted into radiant to provide us with
light
– Converted into thermal to heat up homes/buildings
– Converted into kinetic to make electric motors move
– Can come from a Power Plant, car battery, etc.
– A generator is a device that is used to convert kinetic
energy into electrical energy
– In a power plant, steam is used to spin a turbine which
then spins an electric generator
Food Chain
• When animals eat, they
absorb the chemical
energy of their prey.
• Also, when animals
decompose their
chemical energy is
transferred to the soil
(humus) and other
insects. Even animals
go through energy
transfers.
Our Body!!
• When we move, we also use energy! Our
whole body uses energy transfers to
function: Our cells -> tissues -> organs ->
system.
• When we sweat or shiver our energy is
transferred through our body and then to
anything we touch (i.e. our clothes, the floor,
a person, etc.)
Virtual Lab
• Fill out your Paper and then wait for the class
to be ready to complete the example and
virtual lab.
– Let’s look at a GIZMO example
– Virtual Lab: Energy Conversions