1. Energy
Year 8 Science

2. Energy is the ability to do work.
Nature of Energy
Energy is all around you
You hear energy as sound, you see energy as light, you can feel energy in wind.
Living organisms need energy for growth and movement.
You use energy when you hit a tennis ball, compress a spring, or lift a grocery bag.
Energy is the ability to do work.

3. What is the definition of energy?
Energy is the ability to do work
The ability to make something observable happen
Work happens when a force moves an object.
It is measured in joules (symbol j)
Have students brainstorm different types of forces –they should have learnt about these last year. Help students make the connection between energy, work and force.

4. Law of Conservation of Energy:
All things possess energy even if they are not moving
(There is Action energy and potential energy)
ENERGY CAN NOT BE CREATED OR DESTROYED.
We will be learning about action energy and potential energy. Ask students to turn and talk: Does this mean that the amount of energy in the universe always stays the same?

5. What happens to Energy if it isn’t created or destroyed?
This means the amount of Energy in the Universe will always stay the same.
But what does this mean for energy??? What happens to it?

6. Energy can be transferred or transformed
Energy can be TRANSFERRED to another object
From a cricket bat to a ball OR
Energy can be TRANSFORMED to a different form of energy
Electrical energy to sound energy
Transferred (handover). Transformed (change)
BRAINSTORM DIFFERENT FORMS OF ENERGY

7. Forms of Energy
Energy exists in many forms however there are two main groups
Stored Energy (Potential Energy)
Energy in Action (Action Energy)

8. Forms of Energy
Light energy, sound energy thermal energy and kinetic energy are easily observed, you can observe them acting with your senses. All objects that move have kinetic energy. Electrical energy can be seen if there’s a lightning strike (because it also gives off light energy) but can’t be seen when moving through wires but can be observed powering your ipod or allowing the light in your bedroom to work. Stored energy is known as potential energy because it has the potential to make something happen. There are several different forms of potential energy.

9. Stored Energy
Stored energy is energy that is not in action right now but is ready for action
Chemical, Elastic potential, Gravitational Potential and Nuclear Energy are all forms of stored energy.

10. Chemical Energy
Stored in food and drinks to give you the potential to be active
Stored in fuels like petrol, timber, coal, oil have the potential to be transformed to operate vehicles, keep you warm and generate electricity.
It is the chemical energy stored in food and drinks that gives you the energy to live and be active! The chemical energy in fuels is transformed to operate cars and other vehicles, keep you warm and generate electricity. Chemical energy is stored in a battery, when it is connected in an electric circuit the chemical energy is transformed to electrical energy which in turn is transformed into other types.

11. Nuclear Energy Stored at the centre of atoms
(tiny particles that make up matter)
Transformed into electrical energy at a nuclear power station.
Transformed into thermal energy in nuclear weapons.

12. Gravitational Potential Energy
Potential Energy due to the height of an object
The higher it is the more Gravitational potential energy it has.
Gravitational Potential Energy Transforms into Kinetic Energy.
At the top of a roller coaster ride you have a lot of Gravitational potential energy and not much kinetic energy as you come down the gravitational potential energy is transformed into kinetic energy so the cart gets faster and faster. At the bottom of the ride you have much more kinetic energy but much less gravitational potential energy. Energy can be easily changed back and forth.
EPE let go of one end and stored energy is transformed into kinetic energy.

13. Best idea ever Isaac Newton Discovers Gravity - animation
What was happening in the video?
What types of energy did you notice?
Where any energy transformations taking place?

14. Elastic Potential Energy
This is the energy stored in a stretched spring or elastic band.
Transformed into movement -kinetic energy.
The elastic potential energy stored in stretched trampoline springs allows them to throw you in the air when they spring back into place.

15. Wiley Coyote experiences stored energy!
Video clip:
What was happening in the video?
What types of energy did you notice?
Where any energy transformations taking place?

16. Energy in Action
Kinetic Energy is the energy associated with all moving objects. Eg: Speeding train or falling rocks
Heat, light, sound and electrical energy are examples of Action energy.

17. Heat Energy
Energy due to temperature, sources of heat cause a thermometer’s temperature to increase.
Will transfer from a hotter to a colder place
Kinetic energy can be transformed into heat energy
moving objects rubbing together (friction) will generate heat.
Electrical energy can be transformed into heat energy
Heat can be transformed into kinetic energy
Heat can also move things, e.g. pistons in car engines.

18. Light Energy
Light energy enables plants to grow and make food and oxygen in a process called photosynthesis.
Heat Energy can be transformed into light energy:
burning chemicals, very hot objects and stars release light energy.
Electrical energy can be transformed into light energy.
When you turn on the light

19. Sound Energy
Causes the air and our eardrums to vibrate allows us to hear.
The bigger the vibrations, the louder the sound.
Kinetic energy can be transformed into sound energy and vice versa.
Explosions of sound are used to cause controlled avalanches.

20. Electrical Energy This energy is due to moving charges.
This is used in almost nearly all household appliances.

21. Energy Transfer
Energy can be transferred from one object to another without changing its form.

22. Energy Transformation
Energy can be transformed from one form into a different form.
What happens when you rub your hands together?
You can describe this energy with an arrow flow chart.

23. Energy Transformation
Many energy changes can occur
Sometimes more than one form of energy are produced.

24. Energy Transformation
Electrical energy is very important, it can be converted to many different forms of energy
Devices that convert one form of energy to another are called energy converters.

25. An unavoidable loss Not all energy is converted into useful energy
Some is converted into forms of energy that are wasted.
How does this
demonstrate the Law of
Conservation of energy?

26. An unavoidable loss
Energy loss also occurs (heat energy)
when braking in a car or bike
Jumping on a trampoline
Hitting a tennis ball or cricket ball
Power stations
Energy efficient light globes produce less heat therefore waste less energy.

27. Energy efficiency
Later on you will be completing an assignment on making homes more energy efficient.
The Energy Efficiency of a car, light bulb, heater or any other energy converter is a % measure of its ability to provide useful energy.
Energy Efficiency is important for the environment and life on earth