Energy exists in different forms including mechanical, sound, chemical, thermal, electromagnetic, and nuclear. Energy can change forms but is never created or destroyed according to the law of conservation of energy. Technology has improved energy efficiency by reducing unwanted energy forms like heat and increasing the amount of useful energy from sources.

1. Energy
Chapter 3

2. Energy Exists in Different Forms
• Energy has many different forms
• Almost everything around you requires energy
• Think of one process that requires energy.
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3. Energy
• Energy is the ability to cause change.
• All forms of energy have one point in
common: They cause changes to
occur
– The flow of electrical energy through a
wire causes a cool, dark light bulb to
get hot and glow.

4. Forms of Energy
• Mechanical
• Sound
• Chemical
• Thermal
• Electromagnetic
• Nuclear

5. Mechanical Energy
• The energy that moves objects is mechanical
energy
– Example: The energy you use to brush your teeth

6. Sound Energy
• Sound results from the
vibration of particles in a
solid, liquid or gas
• People and other animals
can detect these tiny
vibrations with structures in
their ear.
• http://www.noiseaddicts.co
m/2009/03/can-you-hear-
this-hearing-test/

7. Chemical Energy
• Energy that is stored in the chemical
composition of matter is chemical energy.
• When wood or gasoline burns, chemical
energy produces heat.

8. Thermal Energy
• The total amount of energy from the
movement of particles in matter is thermal
energy.
• The atoms and molecules in matter are always
moving.
• The energy of this motion in an object is
thermal energy.

9. Electromagnetic Energy
• Electromagnetic energy is transmitted through
space in the form of electromagnetic waves.
• Unlike sound, electromagnetic waves can
travel through empty space.
• These waves include: visible light, x-rays, and
microwaves.

10. Electromagnetic Energy
• X-rays are high energy waves used by doctors
and dentists to look at your bones and teeth.

11. Electromagnetic Energy
• Microwaves can be used to cook food or or
transmit cell phone calls.

12. Electromagnetic Energy
• The sun releases a large amount of
electromagnetic energy, some of which is
absorbed by Earth.

13. Nuclear Energy
• The center of an atom – its nucleus – is a
source for nuclear energy.

14. Nuclear Energy
• A large amount of energy in the nucleus holds
the nuclear particles together.
• When a heavy atom’s nucleus breaks apart, or
when the nuclei of two small atoms join
together, energy is released.
• Nuclear energy released from fusing of small
nuclei to form larger nuclei keeps the sun
burning.

15. Kinetic Energy and Potential Energy
• All forms of energy can be described in terms
of two general types of energy: Kinetic and
potential.

16. Kinetic Energy
• The energy of motion is called kinetic energy.
– It depends on both the object’s mass and the speed of
the object’s movement.
• Kinetic Energy increases as mass increases
– If a bowling ball and soccer ball were moving at the
same speed, the bowling ball would have more kinetic
energy because of its larger mass.
• Kinetic energy increases as speed increases.
– If two identical bowling balls were rolling along at
different speeds, the faster one would have more
kinetic energy because of its greater speed.

17. Potential Energy
• Potential Energy is the stored energy that an
object has due to its position or chemical
composition.

18. Potential Energy
• The most obvious form of potential energy
is potential energy that results from gravity.
Gravity is the force that pulls objects
towards Earth’s surface.
• Another form of potential energy comes
from stretching or compression an object.

19. Think-Pair-Share
• How can you tell kinetic energy and potential
energy apart?

20. Energy Changes Forms But is Never
Lost
• Potential Energy can be changed into kinetic
energy and back into potential energy

21. Think-Pair-Share
• Come up with a scenario where kinetic energy
changes to potential energy and back to the
kinetic energy.

22. Energy is Always Conserved
• The law of conservation states that energy
can neither be created nor destroyed.
• When you observe energy in your daily life, it
may seen that the energy constantly
disappears, but it is just changing forms.

23. Law of Conservation
• Conservation of energy is a balance of energy in
the universe.
• When a soccer ball is kicked, a certain amount of
energy is transferred by the kick.
• The ball gains an equal amount of energy, mostly
in the form of kinetic energy.
• The ball’s kinetic energy decreases as some of
that energy is converted into sound energy and
heat from the friction between the ball and the
ground.

24. Energy Conversions May Produce
Unwanted Forms of Energy
• When energy changes forms, the total amount
of energy is conserved; however, the amount
of useful energy is usually less than the total
amount of energy.
• Example of the fan.

25. Energy Conversions May Produce
Unwanted Forms of Energy
• Energy efficiency is a measurement of usable
energy after an energy conversion.
• You may be familiar with energy-efficient
house-hold appliances.
• Less energy is need to operate appliances that
are energy efficient.

26. Technology Improves Energy
conversion
• In many common energy conversions, most of
the wasted energy is released as heat.
• One example is the common incandescent
light bulb. Only about 5% of the electrical
energy is converted to light. That means 95%
of energy is turned into unwanted forms of
energy.

27. Technology Improves Efficiency
• To decrease this amount of wasted energy,
scientists have investigated several more efficient
types of lights.
• Example: LED Light Bulb: Convert almost all
energy into light. They were dull originally but
scientists have made major improvements. They
are used in TVs, remotes, computers, outdoor
signs, traffic lights and many other objects.

28. Efficient Cars

29. Technology Improves the Use of
Energy Resources
• Much of the energy used on Earth comes from
fossil fuels such as coal, petroleum, and
natural gas; however, the supply of fossil fuels
are limited.
• Scientists are exploring alternative methods of
energy: solar, wind, and water power.

30. Solar Energy
• Solar cells are important in today’s solar
energy technology.
• Solar cells are made of several layers of light-
sensitive material, which convert sunlight
directly into electrical energy.

31. Wind Energy
• For many centuries, people have used kinetic
energy of wind to sail ships.
• Recently, windmills have been used to
generate electrical energy.

32. Water Energy
• The kinetic energy of water can be converted to
electrical energy.
• On the Canadian side, the power plants at Niagara
Falls have the capacity to produce ~ 4.9 million
kilowatts. That's enough to power 3.8 millions
homes.