2. STATES AND FORMS OF ENERGY

3. 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. But “what” is it?

4. Energy is involved when: a bird flies. a bomb explodes. electricity flows in a wire.

5. Nature of Energy Energy can be defined as the “ability to do work”. If an object or organism does work, then the object or organism uses energy. So since it’s the ability to do work, energy’s units are also measured in JOULES or J!!!!

6. States of Energy All forms of energy can be in either of two “states” of energy: Potential energy Kinetic energy So the most common energy conversion is the conversion between potential and kinetic energy.

7. Kinetic Energy Kinetic energy is the “energy of motion or movement”. 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.

8. Kinetic Energy Kinetic Energy is measured by the formula: K.E. = mass x (velocity) 2 2 Remember that the units for energy are JOULES or J!!! Which “variable” will have the greater effect on kinetic energy, mass or velocity? Why?

9. Potential Energy Potential Energy is “stored energy” or “energy of position”. Stored chemically in fuel, the nucleus of atom, and in foods. Or stored because of the work done on it is ready to be used: Stretching a rubber band. Winding a watch. Pulling back on a bow’s arrow. Lifting a brick high in the air.

10. Gravitational Potential Energy Potential energy that is dependent on height is called gravitational potential energy. “The bigger they are the harder they fall” is not just a saying. It’s true. Objects with more mass also have greater G.P.E. We measure G.P.E. as: G.P.E. = mass x gravity x height or = Weight x height Also measured in Joules or J.

11. Elastic Potential Energy Energy that is stored due to being stretched or compressed is called elastic potential energy. In order to calculate elastic potential energy, you have to know the object’s “individual” ability to stretch.

12. 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.

13. Kinetic-Potential Energy Conversion At the point of maximum potential energy, the car has minimum kinetic energy. This same system works for when a basketball is thrown in the air or a pendulum swings from side to side.

14. A B C D E A BC All potential energy (stops for an instant) P.E. = 10 J K.E. = 0 J All potential energy (stops for an instant) P.E. = 9 J K.E. = 1 J All kinetic energy (greatest speed) K.E. = 10 J P.E. = 0 J D E Potential energy & Kinetic energy P.E. = 5 J; K.E. = 5 J Potential energy & Kinetic energy P.E. = 4 J; K.E. = 6 J

15. Ball slows down Ball speeds up

17. The Law of Conservation of Energy Energy can be neither created nor destroyed by ordinary means. It can only be transformed from one form to another. If energy seems to disappear, then scientists look for it – leading to many important discoveries. In 1905, Albert Einstein discovered the only significant exception to this rule. Einstein theorized 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. The formula: E = mc 2 Where “c” represents “speed of light”

18. Forms of Energy Their are six main forms of energy are: Mechanical Chemical Thermal/Heat Electromagnetic Electrical Nuclear Its important to know the difference between “transfer” and “transforming” energy. 1.Transfer means that the energy is moving from one place to another. Ex: Pendulum transfer the energy of one ball to another. 2. Transform means that the energy changes from one form to another. Ex: How solar energy is transformed into food, oil products, moving machinery, etc.

19. What is Mechanical Energy? o Energy due to a object’s motion (kinetic) or position (potential). oThe bowling ball has mechanical energy. oWhen the ball strikes the pins, mechanical energy is transferred to the pins! And some of the energy is transformed into “sound energy”.

20. Examples of Mechanical Energy

21. What is Chemical Energy? o Energy that is available for release from chemical reactions or bonds. oThe chemical bonds in a matchstick store energy that is transformed into thermal energy and electromagnetic energy when the match is struck.

22. Examples of Chemical Energy

23. What is Thermal/Heat Energy? o Heat energy or produces heat o The amount of heat energy of an object determines how active its atoms are. oA hot object is one whose atoms and molecules are excited and show rapid movement. This means a lot of heat energy. oA cooler object's molecules and atoms will show less movement and are not excited. In other words, not a lot of heat energy.

24. What is Electromagnetic Energy? oEnergy that come in the forms of waves. o Includes energy from gamma rays, x-rays, ultraviolet rays, visible light, infrared rays, microwave, and sound/radio bands.

25. What is Electrical Energy? o Energy caused by the movement of electrons. o Easily transferred through power lines and then transformed into other forms of energy.

26. What is 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 (fusion). These two processes are known as nuclear fission and fusion.

27. Nuclear Energy The sun’s energy is produced from a nuclear fusion reaction in which hydrogen nuclei fuse to form helium nuclei. The same notion happens with atomic bomb. Nuclei collide with other nuclei particles and cause a chain reaction which releases large quantities of energy.

28. Nuclear Energy Its important to note that nuclear energy is the most concentrated form of energy. Most of us live within 1-10 miles of the Potrero Hills Power Plant which converts nuclear energy into electromagnetic energy.

29. “Guess What Types of Energy” Game!! What type of energy cooks food in a microwave oven? ELECTROMAGNETIC ENERGY What type of energy is the spinning plate inside of a microwave oven? MECHANICAL ENERGY

30. 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

31. QUIZ TIME! What energy “transformation” occurs when an electric lamp is turned on? ELECTRICAL ENERGY  ELECTROMAGNETIC ENERGY AND THERMAL

32. What types of energy are shown below? Mechanical and Thermal Energy (Don’t forget friction)

33. What type of energy is shown below? Electromagnetic and Chemical Energy

34. What “types of energy” are shown below? Electrical, Mechanical and Electromagnetic Energy

35. What type of energy is shown below? Chemical Energy (yummy)

36. What type of energy is shown below? Thermal Energy and Electrical

37. TICKET OUT THE DOOR/HW FOR TONIGHT Draw a flow map showing the flow of energy “transformations” in a car from starting the vehicle to driving. You should have 5 different types of energy.

38. Energy Transfer Chemical Electrical Sound (mechanical) Light (Electromagnetic) Thermal Mechanical