Energy

What is Energy?• The ability to make things

move/cause change or to do work

• Any change• Every change that occurs

involves energy….changes REQUIRE energy

• SI Unit – Joule ( J )

WorkThe transfer of energy from one object to

another

Work is when a force moves an object

Also SI unit: Joule (J)

Energy is the ability to do work.

You are doing work. Your pencil is doing work. Both of you have energy.

Can you make things move?

• Then you have energy…

• …but there are many different kinds of energy…

Curriculum ConnectionEverything we learn this year is connected in some way and we learn it in a logical order.

Think back to our previous units:

How is energy related to (or how does it build upon what we already learned about) motion and forces?

Review Slide

What is the SI unit for each quantity? Write in your comp book – help each other if you need to.

1.Force

2.Height

3.Work

4.Mass

5.Energy

Chemical Energy• What holds atoms in molecules

together

• Has the “potential” to be released by chemical reactions like burning wood

• FOOD (CPE)

What is Chemical Energy?

o Energy that is available for release from

chemical reactions.

The chemical bonds in a matchstick

store energy that is transformed into thermal energy

when the match is struck.

Examples of Chemical Energy

Electrical Energy• The movement (KE) of

electrons through conductive matter

• newly derived from electrical PE

• Electricity is a form of electrical energy

What is Electrical Energy?

o Energy caused by the movement of

electrons

o Easily transported

through power lines and converted into other forms of

energy

Thermal Energy (HEAT)• The random motion, or

vibration, of atoms in matter

• The faster the atoms vibrate the more heat energy they have

• How we measure temperature

What is Thermal Energy?o Heat energy

o The heat energy of an object determines how active its atoms are.

A hot object is one whose atoms and molecules are excited and show rapid

movement.

A cooler object's molecules and atoms will

show less movement.

Light/Radiant Energy• The energy carried by light

• Yes, whenever you are looking at light, you are looking at energy

What is ElectromagneticEnergy?

o Light energy

o Includes energy from gamma rays, xrays, ultraviolet rays, visible light,

infrared rays, microwave and

radio bands

Mechanical Energy• The total energy of moving

things• PE + KE = ME

• When you ride a bike you use mechanical energy

• Anytime you or an object does work.

What is Mechanical Energy?

o Energy due to a object’s motion

(kinetic) or position (potential).

The bowling ball has mechanical energy.

When the ball strikes the pins, mechanical energy is transferred

to the pins!

Examples of Mechanical Energy

Nuclear Energy• Holds protons and neutrons

together in an atom’s nucleus

• Atoms can split (nuclear fissure) or fuse together (nuclear fusion)

• Powers the sun and nuclear power plants

Sound Energy

• Vibrates air molecules• The air molecules move tiny

bones in your ear• The message of sound then

moves to your brain• Can also vibrate objects

• Falling objects- at the top of the hill, the ball has potential energy. As it rolls down the hill, its potential energy decreases, but as it gains speed its kinetic energy increases.

Energy can be transformed from one

form to another

• Chemical energy in gasoline is changed to heat energy and then to mechanical energy in a car

Energy can be transformed from one

form to another• When you eat, your body

converts the chemical energy in food into thermal energy.

QUIZ TIME!Electrical energy is transported to your house through power lines.

When you plug an electric fan to a power outlet, electrical energy is transform into what type of energy?

MECHANICAL ENERGY

QUIZ TIME!

What energy transformation occurs

when an electric lamp is turned on?

ELECTRICAL ENERGY

ELECTROMAGNETIC/RADIANT ENERGY

What types of energy are shown below?

Mechanical and Thermal Energy(Don’t forget friction)

What type of energy is shown below?

Chemical Energy (CPE)

What types of energy are shown below?

Electrical, Mechanical andElectromagnetic/Radiant Energy

What type of energy is shown below?

Chemical Energy (yummy)

What type of energy is shown below?

Thermal Energy

Energy Transfer

Chemical

Electrical

Electrical

Electrical

Sound(mechanical)

Light(Electromagnetic)

ThermalMechanical

PowerThe rate energy is transformed.

(Rate work is done)

The more power something has, the quicker the energy transforms.

Example) a runner running burns energy more quickly than someone walking, therefore they have more power

Can you think of another example?

What is the difference?

• Kinetic energy: energy of a moving object because of its motion

(Depends on MASS and SPEED)

• Potential energy: stored energy due to its position

“Has the potential to move”

Kinetic = moving [falling apple]

potential = stored (not moving)

The apple has the ability to cause change…therefore, it has energy

If the apple stays in the tree, the energy is stored as potential energy, if it falls, there is a change of motion (kinetic energy)

TYPES OF POTENTIAL ENERGY

Elastic Potential Energy - energy stored by something that can stretch or compress (like a rubber band or a spring)

The stretching of the rubber band shows elastic pot. Energy – it flying through air is kinetic

Gravitational Potential Energy (GPE) – the stored energy for anything that can fall (the energy stored by objects due to their position above the Earth’s surface◦ Depends on the MASS & HEIGHT ABOVE GROUND

Which Type?

Which Type?

Which Type?

Law of Conservation of EnergyAs energy is transformed, it is neither created

or destroyed. It stays the same. It is conserved.

The amount of energy in the entire universe is always the same. It just transforms into different forms.

(Friction can absorb some of the energy, but it doesn’t destroy it)

Which type of energy? How is this the Conservation of Energy? Why

does it eventually stop?

Both Potential and Kinetic.

The friction eventually slows it down.

Friction causes the energy to transform to thermal (heat)

energy.

Kinetic energy and potential combined make thermal energy.

RECAP:-The amount of energy in the Universe never

changes. It just transforms (changes into different forms). The Law of Conservation of Energy.

-There are two main types of energy: Kinetic (motion) and Potential (has the potential for motion)

-There are many other forms of energy that can transform into each other.

-The unit for energy is the joule and energy is simply the ability for something to change.