1. FORMS of ENERGY

2. Energy has different forms. A.The sun gives off energy in the form of heat and light.

3. Energy has different forms. A.The sun gives off energy in the form of heat and light. B.Plants convert sunlight into food.

4. Energy has different forms. A.The sun gives off energy in the form of heat and light. B.Plants convert sunlight into food. C.People convert food energy into muscle movement.

5. 1. Mechanical Energy Energy associated with the motion and stored energy Mechanical Energy = K.E. + P.E.

6. 2. Thermal Energy Energy of atoms When an object’s atoms move faster, its thermal energy increases (object becomes warmer).

7. This molten metal is extremely hot. It contains a great deal of thermal energy.

8. 3. Chemical Energy The energy stored in chemical bonds. When bonds are broken, the released energy can do work. All chemical compounds, including fuels such as coal and gasoline, store energy.

9. This family is using the chemical energy of burning wood to produce thermal energy for heating marshmallows. Forms of Energy

10. 4. Electrical Energy The energy associated with electrons (electric charges) Electric charges can exert forces that do work.

11. 5. Electromagnetic Energy Energy that travels through space in the form of waves What are some examples of electromagnetic energy ?

12. A.Lightning bolts transfer electric charge. B.Galaxies are giant structures in space that typically contain billions of stars. The stars give off enormous amounts of electromagnetic energy.

13. 6. Nuclear Energy The energy stored in atomic nuclei Nuclear fission: releases energy by splitting more massive nuclei into less massive nuclei. Nuclear fusion: releases energy by combining less massive nuclei into more massive nuclei.

14. Assessment Questions 5.The energy stored in the bonds between atoms of a compound is called a.electromagnetic energy. b.chemical energy. c.nuclear energy. d.thermal energy.

15. Assessment Questions 5.The energy stored in the bonds between atoms of a compound is called a.electromagnetic energy. b.chemical energy. c.atomic energy. d.thermal energy. ANS:B

16. Conservation of Energy

17. 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 light bulb – A hair dryer

18. An example of transforming chemical energy is a Car Engine: Chemical P.E. in gasoline is transformed into K.E. of the car as it moves!!

19. Mechanical energy = PE + KE Mechanical energy is due to the position and motion of the object The total amount of potential and kinetic energy in a system is called the mechanical energy In many situations, there is a conversion between potential and kinetic energy

22. What happens to the mechanical energy of an apple as it falls from a tree? Newton’s Apple

23. As the apple falls to the ground, its height decreases. Therefore, its PE decreases. The P.E. is not lost… it is converted into kinetic energy as the velocity of the apple increases. What happens to the mechanical energy?

24. 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!!

26. Just before the apple hit the ground all the PE converted to KE, while the ME remained constant However after it hits the ground there is no PE, no KE, which means there is no ME. What happened to the energy? The ME converted to thermal energy (Ground is a bit hotter after the apple hits the ground then it was before the apple hit the ground)

27. The Law of Conservation of Energy The Law of Conservation of Energy states that energy cannot be created or destroyed Energy is transformed… not destroyed!!

28. Swinging Along Think about the changes in energy when you are on a swing… At what point do you have the most P.E. ? At what point do you have the most K.E.? What happens to the mechanical energy?

29. If I stop pumping while I’m swinging, I stop!! So, where’s the energy?

30. You need to remember friction… Friction causes the kinetic energy to convert to thermal energy (chains get hot)

31. Energy in Your Body Even the energy converted in your body follows the law of conservation of energy. Chemical potential energy is transferred to kinetic energy that allows your body to move!!

32. A Calorie (C) is a unit to measure energy in foods. 1 Calorie is equal to about 4,184 Joules. A person uses about: – 55 Calories while sleeping for 1 hour – 210 Calories while walking for 1 hour – 850 Calories while running for 1 hour

33. Albert Einstein

34. How are energy and mass related E = mc 2 (Einstein's equation) Says that energy and mass are equivalent and can be converted into each other. E  is energy m  is mass c  is the speed of light. Speed of light is an extremely large number, 3.0 × 10 8 meters per second.

35. Change in Law A tiny amount of matter can produce an enormous amount of energy. In nuclear fission and fusion reactions, however, large amounts of energy are released by the destruction of very small amounts of matter. The law of conservation of energy has been modified to say that Mass and energy together are always conserved.