2. Who’s doing work?

3. Work is only done by a force on an
object if the force causes the object
to move in the direction of the force.
Objects that are at rest may
have many forces acting on them,
but no work is done
if there is no movement.

4. W = F·d Work, the product of the force exerted on
an object and the distance the object
moves in the direction of the force.
W = F·d

5. the time rate of doing work; or the time rate transfer of energy.
Power,
by definition, is
the time rate of doing work;
or the time rate transfer of energy.
P = W / t

6. P = W / t work over time. My friend, Power, has been so stressed.
His boss keeps
making him
work over time.
P = W / t

7. Energy click on energy for a short video

8. Energy: Forms and Changes

9. Nature of Energy Energy is all around you!
You can hear energy as sound.
You can see energy as light.
And you can feel it as wind.

10. Nature of Energy You use energy when you: hit a softball.
lift your book bag.
compress a spring.

11. Living organisms need energy for growth and movement.
Nature of Energy
Living organisms need energy for growth and movement.

12. Nature of Energy Energy is involved when: a bird flies.
a bomb explodes.
rain falls from the sky.
electricity flows in a wire.

13. Energy comes in many forms: mechanical, electrical , magnetic, solar,
the ability to do work
Energy comes in many forms:
mechanical, electrical , magnetic, solar,
thermal, chemical, etc...
The SI unit of energy is the Joule.

14. Energy
Review how the forms of energy are classified. Use the Forms of Energy handout to begin this discussion.

15. Energy Kinetic Energy Potential Energy
Stored energy and the energy of position
Kinetic Energy
Motion of waves, electrons, atoms, molecules, and substances
Review how the forms of energy are classified. Use the Forms of Energy handout to begin this discussion.

16. Stored energy and the energy of position
Potential Energy
Stored energy and the energy of position

17. Nuclear Energy Chemical Energy Potential Energy Gravitational Energy
Energy stored in the bonds of atoms and molecules
Nuclear Energy
Energy stored in the nucleus of an atom – the energy that holds the nucleus together
Potential Energy
Stored energy and the energy of position
Gravitational Energy
Energy of place or position
Elastic Energy
Energy stored in objects by the application of force.

18. Motion of waves, electrons, atoms, molecules, and substances
Kinetic Energy
Motion of waves, electrons, atoms, molecules, and substances

19. Kinetic Energy Radiant Energy Thermal Energy Sound Energy
Electromagnetic energy that travels in transverse waves
Thermal Energy
Internal energy in substances – vibration or movement of atoms and molecules in substances
a.k.a. “heat”
Kinetic Energy
Motion of waves, electrons, atoms, molecules, and substances
Sound Energy
Movement of energy through substances in longitudinal waves
Electrical Energy
Movement of electrons
Mechanical Motion
Movement of substance from one place to another

20. GPE = mgh Potential Energy Stored Energy
gravitational potential energy
GPE = mgh
m - mass of object in kg
g - acceleration of gravity in m/s2
h - height of object, in m
GPE – gravitational potential energy in J

21. KE = 1/2 mv2 Kinetic Energy energy of motion
All moving objects that
have mass have kinetic energy.
KE = 1/2 mv2
m - mass of the object in kg
v - speed of the object in m/s
KE - the kinetic energy in J

22. Different Types of Energy.

23. Kinetic Energy
Anything that moves has kinetic energy.

24. Gravitational Potential Energy (GPE)
Anything above the ground has gravitational potential energy i.e. anything that can fall, like ski jumpers, aeroplanes and climbers.

25. Nuclear Energy Released only from nuclear reactions
The sun and all of the stars. Hydrogen bomb (Fusion) Nuclear power plants

26. Sound Energy
Anything noisy gives off sound energy like vocal chords, speakers and instruments.

27. Chemical Energy
Anything with stored energy which can be released by a chemical reaction has chemical energy, things like food fuels and batteries.

28. Radiant Energy also called electromagnetic energy All life on Earth depends upon radiant energy from the sun Examples: radio waves, microwaves, X-rays,

29. Heat/Thermal Energy
Anything with a temperature above absolute zero (-273°C) has heat energy. That means everything has some thermal energy.

30. Light Energy
Anything luminous gives off light energy, like the sun, light bulbs , candles and glow worms.

31. Electrical Energy
Electrical energy is very useful, because its easily converted into other forms – wherever there's a current flowing there's electrical energy.

32. Elastic Energy
Anything stretched, has elastic energy – things like rubber bands, springs, knickers, elastic etc

33. Different types of energy click on link above for a video:
thermal
light
sound
elastic
gravitational
kinetic
electrical
chemical
nuclear
Can you think of examples of each
type of energy?

34. Energy transfer Energy can be changed from one form to another.
For example:
Chemical energy in food is converted to thermal energy
and kinetic energy by our bodies.
Gravitational energy in a ball is converted to kinetic energy when it falls to the ground.
What other energy transfers can you think of?

35. Energy comes in many forms: mechanical, electrical , magnetic, solar,
the ability to do work
Energy comes in many forms:
mechanical, electrical , magnetic, solar,
thermal, chemical, etc...
The SI unit of energy is the Joule.

36. Energy
Review how the forms of energy are classified. Use the Forms of Energy handout to begin this discussion.

37. Energy Kinetic Energy Potential Energy
Stored energy and the energy of position
Kinetic Energy
Motion of waves, electrons, atoms, molecules, and substances
Review how the forms of energy are classified. Use the Forms of Energy handout to begin this discussion.

38. Stored energy and the energy of position
Potential Energy
Stored energy and the energy of position

39. Nuclear Energy Chemical Energy Potential Energy Gravitational Energy
Energy stored in the bonds of atoms and molecules
Nuclear Energy
Energy stored in the nucleus of an atom – the energy that holds the nucleus together
Potential Energy
Stored energy and the energy of position
Gravitational Energy
Energy of place or position
Elastic Energy
Energy stored in objects by the application of force.

40. Motion of waves, electrons, atoms, molecules, and substances
Kinetic Energy
Motion of waves, electrons, atoms, molecules, and substances

41. Kinetic Energy Radiant Energy Thermal Energy Sound Energy
Electromagnetic energy that travels in transverse waves
Thermal Energy
Internal energy in substances – vibration or movement of atoms and molecules in substances
a.k.a. “heat”
Kinetic Energy
Motion of waves, electrons, atoms, molecules, and substances
Sound Energy
Movement of energy through substances in longitudinal waves
Electrical Energy
Movement of electrons
Mechanical Motion
Movement of substance from one place to another

42. What impacts an object’s GPE?
Who has more energy?
Who has more energy?

44. GPE = Wh Potential Energy Stored Energy gravitational potential energy
W – Weight of object in N
h - height of object, in m,
GPE – gravitational potential energy in J

45. Roller Coaster Conversions

47. The NEED Project

48. Law of Conservation of Energy
“Energy can be neither created nor destroyed.
It may only change forms.”
energy before the event = energy after the event
Examples:
A dropped object loses gravitational PE as it gains KE.
A block slides across the floor and comes to a stop.
A compressed spring shoots a ball into the air.

49. Law of Conservation of Energy
Watch the video and take notes on the law of conservation of energy

50. Turning on the Light in Your Closet
Thermal
Sound
Radiant
Electrical
Motion

51. Describe energy transfer in each device
burning match
portable torch
microphone
radio
television
catapult
mobile phone
car

52. Describe energy transfer in each device
burning match
microphone
radio
television
car
chemical to thermal and light
sound to electrical
electrical to sound and thermal
electrical to sound and light and thermal
chemical to kinetic and sound and thermal
In all these transfers the energy is not lost, it is conserved.
Energy cannot be destroyed or created.

55. Look at the scenes on the slides that follow.
Energy poker
Look at the scenes on the slides that follow.
Make a bid for the number of energy transfers that you can see. The person with the highest bid has to explain where they are. If they fail to find that number they lose.
Can you win at energy poker?
Let’s look at an example first…

56. First Example… Energy poker score: 1
Sunlight energy converted into heat to boil the water for tea