1. Energy: Forms and Changes

2. Part 2

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

4.  You use energy when you: hit a softball. lift your book bag. compress a spring.

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

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

7. Nature of Energy  What is energy that it can be involved in so many different activities? We know that energy is the ability to do work (video).work If an object or organism does work (exerts a force over a distance to move an object) the object or organism uses energy. E=FxD

8. Nature of Energy  Because of the direct connection between energy and work, energy is measured in the same unit as work: joules (J).  In addition to using energy to do work, objects gain energy because work is being done on them.

9. Types of Energy Potential- stored energy Kinetic- the energy of motion

10. Potential Energy  Potential Energy is stored energy. Stored chemically in fuel, the nucleus of atom, and in foods. Or, it is stored because of the work done on it:  Stretching a rubber band.  Winding a watch.  Pulling back on a bow’s arrow.  Lifting a brick high in the air.

11. Review  What is the potential energy of a 3 kilogram-ball that is on the ground?

12. Review  What is the potential energy of a 10-newton book that is placed on a shelf that is 2.5 meters high?

13. 5 Main Types of Potential Energy  Chemical  Mechanical  Nuclear  Gravitational  Elastic

14. Chemical Energy  is energy that is stored in the bonds of atoms and molecules. It is the energy that holds these particles together. Biomass, Petroleum, Natural gas, and propane are examples of stored chemical energy.

15. Stored Mechanical Energy  Stored Mechanical Energy is energy stored in objects by the application of a force. Compressed springs Stretched rubber bands

16. Nuclear Energy  Nuclear Energy is energy stored in the nucleus of an atom; it is the energy that holds the nucleus together.  The energy can be released when the nuclei are combined or split apart. Fission vs Fusion

17. Gravitational Potential Energy  Potential energy that is dependent on height is called gravitational potential energy. g=9.82 PE=mgh

18. Elastic Potential Energy  Energy that is stored due to being stretched or compressed is called elastic potential energy.  Road Runner: http://www.youtube.com/watch?v=J nj8mc04r9E&feature=related Road Runner: http://www.youtube.com/watch?v=J nj8mc04r9E&feature=related

19. Gravitational Potential Energy  If you stand on a 3-meter diving board, you have 3 times the G.P.E, than you had on a 1-meter diving board.  Why?

20. Gravitational Potential Energy  “The bigger they are the harder they fall” is not just a saying. It’s true. Objects with more mass have greater G.P.E.  The formula to find G.P.E. is G.P.E. = Weight X Height. Calculate your Gravitational Potential Energy?.......................

21. Potential Energy Converted to Kinetic Energy

22. Kinetic-Potential Energy Conversion Roller coasters work because of the energy that is built into the system. Initially, the cars are pulled mechanically up the tallest hill, giving them a great deal of potential energy. From that point, the conversion between potential and kinetic energy powers the cars throughout the entire ride.

23. Kinetic-Potential Energy Conversions  As a basketball player throws the ball into the air, various energy conversions take place. Him Ball

24. So, what is Kinetic Energy?  Pool:http://www.neok12.com/php/ watch.php?v=zX48506e050646577 a5f6d41&t=Energy-and-Work Pool:http://www.neok12.com/php/ watch.php?v=zX48506e050646577 a5f6d41&t=Energy-and-Work

25. Kinetic Energy  The energy of motion  The faster an object moves, the more kinetic energy it has.  The greater the mass of a moving object, the more kinetic energy it has.  Kinetic energy depends on both mass and velocity.

26. Kinetic Energy The kinetic energy of an object is the energy it possesses because of its motion. K.E. = mass x velocity 2

27. Example I do……..  A 50-kilogram boy and his 100- kilogram father went jogging. Both ran at a rate of 5 m/sec. Who had more kinetic energy?  Who do you think and why?

28. I do solution  Although the boy and his father were running at the same speed, the father has more kinetic energy because he has more mass.

29. Example WE do  What is the kinetic energy of a 3- kilogram ball that is rolling at 2 meters per second?  Start with writing down the equation………………………….

30. Solution WE do…

31. Example YOU do……  What is the kinetic energy of a 2,000- kilogram boat moving at 5 m/sec?

32. Class/Homework  1.Kinetic vs Potential #2  2.Complete energy problems

33. Part 3  Energy Forms and Changes

34. Forms of Energy The five main forms of energy are: Heat Chemical Electromagnetic Nuclear Mechanical

35. Heat EnergyHeat Energy (heat energy video)  The internal motion of the atoms is called heat energy, because moving particles produce heat.  Heat energy can be produced by friction.  Heat energy causes changes in temperature and phase of any form of matter.

36. Convection/Conduction  Convection (vid): Convection Heat is transferred from one place to another. Convection takes place when heated molecules move from one place to another, taking the heat with them. ConductionConduction (vid): Heat is transferred from one object to another. As one molecule is heated it begins to move and shake rapidly. As it does so, it passes some of its heat energy to other molecules around it. Through this process, all the molecules of an object pass heat from one to another, until they are all hot.

37. Chemical Energy  Chemical Energy is required to bond atoms together.  And when bonds are broken, energy is released.

38. Chemical Energy  Fuel and food are forms of stored chemical energy.

39. Electromagnetic Energy Electromagnetic Energy (vid-how do microwaves work)  Power lines carry electromagnetic energy into your home in the form of electricity.

40. Electromagnetic Energy  Light is a form of electromagnetic energy.  Each color of light (Roy G Bv) represents a different amount of electromagnetic energy.  Electromagnetic Energy is also carried by X-rays, radio waves, and laser light.

41. Nuclear Energy  The nucleus of an atom is the source of nuclear energy.

42. Nuclear Energy  When the nucleus splits (fission), nuclear energy is released in the form of heat energy and light energy.  Nuclear energy is also released when nuclei collide at high speeds and join (fuse).

43. Nuclear Energy The sun’s energy is produced from a nuclear fusion reaction in which hydrogen nuclei fuse to form helium nuclei.

44. Nuclear Energy  Nuclear energy is the most concentrated form of energy.

45. Mechanical Energy  When work is done to an object, it acquires energy. The energy it acquires is known as mechanical energy.  Mechanical Energy=PE+KE

46. Mechanical Energy  When you kick a football, you give mechanical energy to the football to make it move.

47. Mechanical Energy When you throw a balling ball, you give it energy. When that bowling ball hits the pins, some of the energy is transferred to the pins (transfer of momentum).

48. Energy Conversion  Energy can be changed from one form to another. Changes in the form of energy are called energy conversions.

49. Energy conversions  All forms of energy can be converted into other forms. The sun’s energy through solar cells can be converted directly into electricity. Green plants convert the sun’s energy (electromagnetic) into starches and sugars (chemical energy).

50. Other energy conversions In an electric motor, electromagnetic energy is converted to mechanical energy. In a battery, chemical energy is converted into electromagnetic energy. The mechanical energy of a waterfall is converted to electrical energy in a generator.

51. Energy Conversions  In an automobile engine, fuel is burned to convert chemical energy into heat energy. The heat energy is then changed into mechanical energy.

52. Chemical  Heat  Mechanical

53. Ball slows down Ball speeds up

54. The Law of Conservation of Energy  Energy can be neither created nor destroyed by ordinary means. It can only be converted from one form to another. If energy seems to disappear, then scientists look for it – leading to many important discoveries.

55. Law of Conservation of EnergyLaw of Conservation of Energy (vid)  In 1905, Albert Einstein said that mass and energy can be converted into each other.  He showed that if matter is destroyed, energy is created, and if energy is destroyed mass is created. 2  E = MC

56. Vocabulary Words energy mechanical energy heat energy chemical energy electromagnetic energy nuclear energy kinetic energy potential energy gravitational potential energy energy conversion Law of Conservation of Energy