Download Forms of Energy * Day 4

Energy—Day 4
Materials Needed:
• Writing Utensil
• Folder
• Notebook
Please pick up the handout on the
front table!
1. Give an example in which one form of energy
changes to another form of energy.
2. Give an example in which PE changes to KE.
3. Give an example in which KE changes to PE.
4. What is the unit for energy?
Agenda
BLAM
Notes over different forms of energy.
Discuss the Law of Conservation of Energy.
Q1: WHY IS DENSITY USEFUL FOR
IDENTIFYING ELEMENTS?
A.
Density predicts whether objects float.
B.
Density varies at different temperatures.
C.
Density is often unique to each element.
D.
Different elements have the same densities.
SC8.2.1.g DOK 2
Q2: WHAT IS THE MOST DENSE SOLID
SHOWN ON THE TABLE?
A.
B.
C.
D.
mercury
pyrite
silver
zinc
SC8.2.1.g DOK 2
MATH BOOSTER DAY 4
A shop owner increased the
selling price of a shirt from $20 to
$27. By what percentage was the
price increased?
GREEK AND LATIN DAY 4
Greek /Latin Picture
dynam-erggravkilo-
kine-
OBJECTIVE DAY 4
1. I will know (knowledge): the
different forms of energy and the
law of conservation of energy.
2. I will be able to (skill): apply the
law of conservation of energy.
1. Give an example in which one form of energy
changes to another form of energy.
Answer: A light bulb, in which the electrical
energy changes to light energy or sound
energy or both.
2. Give an example in which potential energy
changes to kinetic energy.
Answer: A marker falling off a desk.
3. Give an example in which kinetic energy
changes to potential energy.
Answer: When you throw a ball up in the air.
4. What is the unit for energy?
Answer: joules
A1: WHY IS DENSITY USEFUL FOR
IDENTIFYING ELEMENTS?
A. Density predicts whether objects float.
Objects of various densities will float, but do not
identify elements.
B. Density varies at different temperatures.
Density does not vary with temperature.
C. Density is often unique to each element.
Different elements tend to have different
densities.
D. Different elements have the same densities.
Different elements tend to have different
densities.
SC8.2.1.g DOK 2
A2: WHAT IS THE MOST DENSE SOLID
SHOWN ON THE TABLE?
A. mercury
13.55 g/cm3 is the most dense liquid, not solid.
B. pyrite
5.02 g/cm3 is not the most dense solid.
C. silver
10.50 g/cm3 is the most dense solid.
D. zinc
7.13 g/cm3 is not the most dense solid.
SC8.2.1.g DOK 2
MATH BOOSTER DAY 4 -- ANSWER
A shop owner increased the selling price of a shirt from
$20 to $27. By what percentage was the price increased?
Increase in the price = $27 - $20 = $7
Percentage increase in the price =
× 100
= (7 ÷ 20) × 100
= 35 %
Energy classifications:
1. kinetic energy
2. potential energy
3. energy in fields such as those
produced by electromagnetic waves
Each of these forms of energy can be
converted into other forms of energy.

What are the major forms of energy?


What are the major forms of energy?
The major forms of energy are:
mechanical energy
thermal energy
chemical energy
electrical energy
electromagnetic energy
nuclear energy
Mechanical Energy
 The energy associated with the motion and
position of everyday objects is mechanical
energy.
 Mechanical energy is the sum of an object’s
potential energy and kinetic energy.
 What does sum mean?
 ADDITION
Thermal Energy
 The total potential energy and
kinetic energy of all the
microscopic particles in an object
make up its thermal energy.
 When an object’s atoms move
faster, its thermal energy
increases, and the object
becomes warmer.
This molten
metal is
extremely hot.
It contains a
great deal of
thermal energy.
Electrical Energy
 Electrical energy is the energy associated
with electric charges.
CHEMICAL ENERGY:
Chemical Energy:
The energy stored in
chemical bonds.
Electromagnetic Energy
 Electromagnetic energy is a form of
energy that travels through space in the form
of waves.
Visible light and X-rays are examples of
electromagnetic energy.
Nuclear Energy
The energy stored in
atomic nuclei is known as
nuclear energy.
Turn to a partner:
Discuss what fission and
fusion are.
Do you remember???????
•
•
Nuclear fission releases energy by
splitting nuclei apart.
Nuclear fusion releases energy
when less massive nuclei combine
to form a more massive nucleus.
The Law of Conservation of
Energy states that energy cannot
be created or destroyed, it can
only change form.
An example:
As you light a
match energy
is converted
from one form
to another.
The work done by friction changes kinetic
energy into thermal energy.

•
•
Friction within machinery reduces
efficiency. Friction is a major cause of
energy consumption in cars and factories.
In many cases, most of a falling object’s
potential energy is converted into thermal
energy because of air resistance.
 Explain
why speed skaters are slowed
down, even though they slide quickly
over smooth ice.
 They
are slowed down by friction with
the air and the surface of the ice.
The
gravitational potential
energy of an object is
converted to the kinetic
energy of motion as the
object falls.
• An
avalanche brings tons of snow
from the top of a mountain to the
valley floor.
• The elastic potential energy of a
compressed spring is converted
into kinetic energy as the spring
expands.

Some gulls use energy conversion to obtain
food by dropping oysters onto rocks. Kinetic
energy causes the shell to break on collision
with the rock.
Energy Conversion in Pendulums
A pendulum consists of a weight
swinging back and forth from a rope
or string.
AT THIS POINT THE
ENERGY OF POSITION
IS FULL, SO IT HAS PE!
WHILE IT IS MOVING IT HAS
KINETIC ENERGY, BUT IT ALSO
HAS ENERGY OF POSITION.
THERE IS NO LONGER ANY
PE BUT THERE IS KE!
FINALLY, THERE IS NO
MOVEMENT SO THERE IS
ONLY ENERGY OF POSITION.
THE TOTAL AMOUNT
OF ENERGY IS
CONSERVED!
Summary:
Energy Conversion in Pendulums
•
•
•
At the highest point in its
swing, the pendulum has
zero KE and maximum PE.
As the pendulum swings
downward, PE is converted
to KE.
At the bottom of the swing,
the pendulum has maximum
KE and zero PE.
Energy Conversion
and the Pole Vault
In the pole vault, an
athlete uses a
flexible pole to
propel it over a high
bar.
1. Some of the pole-vaulter’s kinetic
energy is converted into elastic
potential energy as the pole bends.
2. The pole springs back into shape,
propelling the pole-vaulter upward.
3. As the pole-vaulter rises, the kinetic energy
decreases while the gravitational potential
energy increases.
4. Once the highest point has been reached,
the gravitational potential energy begins to
convert back to kinetic energy.
Equation:
Mechanical energy =KE +PE
PE = 10 J
KE = ?
ME = ?
KE = 0 J
WHY?
GROUP PRACTICE
NO
MOVEMENT
ME = 10 J
½ WAY DOWN
KE = ? KE = 5 J
PE = ? PE = 5 J
ME = ?
ME = 10 J
NANOSECOND BEFORE IT
HITS THE GROUND
KE = ?
PE = ?
KE = 10 J
PE = 0
ME = ?
ME = 10 J
SMALL
GROUP:
Explain:
1. What you observed about
the mechanical energy (ME)
as the ball dropped.
2. What you observed
happened to KE and PE
as the ball dropped?
SMALL
GROUP
--
ANSWER
1. The Mechanical Energy
stayed the same at the top,
½ way down, and at the bottom.
(ME is the total energy!)
The ME was always 10 J.
2. The KE & PE switched places!
At the top:
KE = 0 PE = 10 J
At the bottom
KE = 10 J PE = 0
The PE was converted to KE as it fell!
Nonrenewable Energy Resources
Nonrenewable energy
resources exist in
limited quantities and,
once used, cannot be
replaced except over
the course of millions
of years.
Nonrenewable Energy Resources
Small Group: Discuss the major
nonrenewable sources of energy.
Nonrenewable energy resources include
oil, natural gas, coal, and uranium.
Fossil fuels
Oil, natural gas, and coal are known
as fossil fuels.
• They were formed
underground from the
remains of once-living
organisms.
• Fossil fuels account for
the great majority of the
world’s energy use.
• These fuels are not
distributed evenly
throughout the world.
Crude oil is
pumped out of
the ground,
refined, and
turned into
gasoline, fuel oil,
and other oil
products.
Renewable Energy Resources
Renewable energy
resources are resources
that can be replaced in a
relatively short period of
time.
Renewable Energy Resources
Small group: Discuss the major
renewable sources of energy.
Renewable energy resources include
hydroelectric, solar, geothermal, wind,
biomass, and, possibly in the future,
nuclear fusion.
1. A 2 kg heavy ball falls from a 3 m shelf. Just
before hitting the floor, what is its kinetic
energy?
 Answer : According to the Law of
Conservation of Energy, total energy at the top
will be equal to the total energy at the bottom.
 Total energy at top = Total energy at bottom
 PE = mgh

= (2 kg)(9.8 m/s2)(3 m)
PE = 58.8 J
(We know that the KE & PE are switched. )
Therefore,
KE = 58.8 J
1. Can you think of any example in which
you can create something out of nothing
or destroy something completely?
2. What types of energy are converted
when you use a cell phone?
1. Can you think of any example in which you can create
something out of nothing or destroy something
completely?
 Answer: We cannot create something out of
nothing or destroy something completely.
2. What types of energy are converted when you use a
cell phone?
 Answer : the electrical energy from the
battery changes sound energy & light energy.
Physical Science Text Book
1. Students will read pages 450 – 457
2. Students will create and complete the
Thinking Visually Chart on page 468.
3. Students will answer questions
#8; #10; #17; and #19 on page 469.
Give examples of renewable and
nonrenewable resources.