2. Nature of Energy EEEEnergy is all around you! YYYYou can hear energy as sound. YYYYou can see energy as light. AAAAnd you can feel it as wind.

3. Energy is usually described as kinetic or potential

4. Thermal or Heat Energy  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.

5. Chemical Energy  Chemical Energy is required to bond atoms together.  And when bonds are broken, energy is released.  Fuel and food are forms of stored chemical energy

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

7. Electromagnetic Spectrum Increasing Energy

8. Electromagnetic Energy  Power lines carry electromagnetic energy into your home in the form of electricity.

9. Nuclear Energy  The nucleus of an atom is the source of 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).

10. Nuclear Power Plant

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

12. Mechanical Energy  Mechanical energy is due to the position and motion of the object.  When work is done to an object, it acquires energy. The energy it acquires is known as mechanical energy.

13. Mechanical Energy  What happens to the mechanical energy of an apple as it falls from a tree?

14. Mechanical Energy  As the apple falls to the ground, its height decreases.  Therefore, its GPE decreases. Potential energy that is dependent on height is called gravitational potential energy.  The potential energy is not lost… it is converted into kinetic energy as the velocity of the apple increases.  What happens to the mechanical energy?

15. Mechanical Energy  The mechanical energy does not change because the loss in potential energy is simply transferred into kinetic energy.  The energy in the system remains constant!!

16. Swinging Along  Think about the changes in energy when you are on a swing…  At what point do you have the most potential energy?  At what point do you have the most kinetic energy?  What happens to the mechanical energy?

17. Conservation of Energy  Energy is transformed… not destroyed!!

18. The Law of Conservation of Energy The law of conservation of energy states that energy cannot be created or destroyed. Energy can be changed from one form to another. Changes in the form of energy are called energy conversions.

19. Energy Conversion Examples

20. The Law of Conservation of Energy Even when energy changes form from electrical to thermal and other energy forms as in the hair dryer shown energy is never destroyed.

21. The Law of Conservation of Energy  The Law of Conservation of Energy states that energy cannot be created or destroyed.  The big picture… the total energy in the universe remains constant.

22. Changing Forms of Energy  Energy is most noticeable as it transforms from one type to another.  What are some examples of transforming electrical energy?  A lightbulb  A hair dryer

23.  The most common energy conversion is between potential and kinetic energy.  All forms of energy can be in either of two states:  Kinetic is the energy of motion.  Potential is stored energy Potential to Kinetic

24. Changing forms of Energy  An example of transforming chemical energy is a car engine.  Chemical potential energy in gasoline is transformed into kinetic energy of the car as it moves!!

25. Energy transfer

26. Photosynthesis  Photosynthesis changes light energy into food (chemical) energy.  Plants convert the energy of sunlight into the energy of chemical bonds of carbohydrates http://www.eia.doe.gov/kids/energyfacts/source s/renewable/images/photosynthesis1.gif

27. Digestion is the process in the body that breaks these chemical bonds and releases the chemical energy in foods This chemical potential energy is changed into kinetic energy as your body moves Energy conversion

28. Conserving Energy  When you “use” energy by turning on a light, you are really converting energy from one form (electricity) to other forms (light and heat).

29. How does the bulb light up? What forms of energy are seen?  The bulb gets its energy from the battery.  There is chemical energy in the battery  Electrical energy in the wires  Thermal energy in the bulb filament  Light energy and thermal energy seen from the bulb.  Energy changes form to light the bulb.

30. Conserving Energy Conserving Energy  Electric power plants don’t make electrical energy.  Energy cannot be created.  Energy CAN be converted from other forms of energy such as chemical, solar, or nuclear energy.

31. Conserving Energy  An average electric power plant puts out 1,000,000 kwh of electrical energy per hour.  That means 120 power plants are burning up resources each hour just to run light bulbs!

32. Solar Energy Solar Power, along with wind and hydroelectric account for most of the renewable energy source available to use. Solar energy can be collected by humans through photovoltaics or solar panels.

34.  What do the photovoltaic and the wheat plant, shown in the images below, have in common?  Photovoltaic Wheat

35.  ANSWER: They both convert sunlight, (electromagnetic energy), into chemical potential energy  The photovoltaic absorbs solar energy and stores it as chemical potential energy in batteries.  The leaves of the wheat plant absorb solar energy which is (mainly) stored as chemical potential energy in compounds called carbohydrates.

37. Kinetic Energy  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.

38. Kinetic Energy K.E. = mass x velocity 2 What has a greater effect on kinetic energy, mass or velocity? Why? the velocity because it is being squared so it is increasing by a factor of 4

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

40. Ball slows down Ball speeds up At the point of maximum potential energy, the car has minimum kinetic energy.