1. Energy Transformations

2. What is energy?
Energy is the capacity to do work or produce heat.

3. Potential Energy-stored energy and the energy of position
Two Types of Energy
Potential Energy-stored energy and the energy of position
Kinetic Energy-working energy in motion

4. Forms of Energy Chemical energy Electrical energy Nuclear energy
Mechanical energy
Thermal energy
Light energy
Sound energy
Gravitational energy

5. Chemical Energy
Chemical energy is the energy stored in the bonds of atoms and molecules.
Chemical energy is potential energy.

6. Electrical Energy
Electrical energy is delivered by tiny charged particles called electrons, typically moving through a wire.
Electrical energy is kinetic when the current is flowing.
Electrical energy is potential when the circuit is open and the current is not flowing.

7. Mechanical Energy Mechanical energy can be both potential and kinetic.
When potential: Mechanical energy is the energy stored in objects by tension (stretched rubber bands).
When kinetic: Mechanical energy is the energy stored in the movement of objects (hammering a nail).

8. Thermal Energy
Thermal energy is heat, the vibration and movement of the atoms and molecules within a substance.
Thermal energy is kinetic energy.

9. Radiant Energy Light energy Moves in waves
Radiant/light energy is kinetic energy.

10. Sound Energy
Sound energy is the movement of energy through substances in waves. Sound is produced when a force causes an object to vibrate.
Sound energy is kinetic energy.

11. Gravitational Energy
Gravitational energy is the energy an object possesses because of its position in a gravitational field.
Gravitational energy is a form of potential energy.

12. Tracking Energy Transformations
As the mountain biker pedals, his leg muscles transform chemical energy into mechanical energy.
Mechanical energy of his leg muscles transforms into mechanical energy of the bicycle as he pedals.

13. Tracking Energy Transformations
Some of this energy transforms into potential gravitational energy as he moves up the hill.
Also, some energy is transformed into thermal energy.
His body is warmer because chemical energy is being released

14. Tracking Energy Transformations
The energy transformations that occur when people exercise, when cars run, when living things grow and even when stars explode, all produce thermal energy.

15. Law of Conservation of Energy
Energy is never created or destroyed.
The only thing that changes is the form in which energy appears.
Example: When the biker is resting at the summit, all his original energy is still around. Some of the energy is in the form of potential gravitational energy, which he will use as he coasts down the hill. Some of this energy was changed to thermal energy by friction in the bike. Chemical energy was also changed to thermal energy in the biker’s muscles, making him feel hot As he rests, this thermal energy moves from his body to the air around him. No energy is missing--- it can all be accounted for.

16. Potential energy is converted into kinetic energy.
Before the yo-yo begins its fall it has stored energy due to its position. At the top it has its maximum potential gravitational energy. As it starts to fall the potential gravitational energy begins to be changed into kinetic mechanical energy. At the bottom its potential energy has been converted into kinetic energy so that it now has its maximum kinetic energy.

17. Potential energy is converted into kinetic energy.
A waterfall has both potential gravitational and kinetic mechanical energy. The water at the top of Bridal Veil Falls has stored potential energy. When the water begins to fall, its potential energy is changed into kinetic energy.

18. Energy Changes Form
A car engine burns gasoline, converting the chemical energy in gasoline into mechanical energy. Solar cells change radiant light energy into electrical energy. Energy changes form, but the total amount of energy in the universe stays the same.

19. Energy Changes Form
Hybrid cars that use an electric motor and a gasoline engine for power are now available. Hybrid cars make energy transformations more efficient so the car can travel farther on a gallon of gas.

20. Energy Changes Form
You wake up. It's a cool, sunny day, You think you'll go for a bike ride. But first you eat a good healthy breakfast. You are taking the chemical energy stored in food into your own body. Any time energy is stored, it's called potential energy. It's available for later use. Without you needing to think about it, the cells in your body will break down the chemical bonds in the food and release the energy in those bonds. You'll use the energy to stay warm, to grow, to keep your internal organs working, and to move your muscles.

21. Energy Changes Form
And you are moving. You jump up from the table, grab a jacket, head out the door. You hop on your bicycle.
The energy of motion is called kinetic/mechanical energy. As you pump your legs, the bicycle starts to roll. Your kinetic/mechanical energy is being transferred to the bicycle.

22. Energy Changes Form
Back at home, you turn on a radio. It runs on electrical energy which travels along the wires that connect a power plant to your home. The electrical energy used by the radio is converted into sound energy.
Sound is another form of kinetic energy--it's air in motion. You can move your muscles to make sound too. For example, you can hit a drum, sing or shout, or strum on a guitar. The guitar strings, vocal cords, or drumhead, once set in motion, make the air around them move.

23. Transforming Chemical Energy
The matter contained in living organisms contains chemical energy. When organisms die, chemical compounds in their biomass break down. Bacteria, fungi, and other organisms help convert these chemical compounds to simpler chemicals that can be used by other living things.

24. Transforming Chemical Energy
Thermal energy also is released as these changes occur.
Example: A compost pile can contain plant matter, such as grass clippings and leaves. As the compost pile decomposes, chemical energy is converted into thermal energy. This can cause the temperature of a compost pile to reach 60° C.

25. Transforming Electrical Energy
Every day you use electrical energy. When you flip a switch, or turn on a radio or television, or use a hair drier, you are transforming electrical energy to other forms of energy.

26. Transforming Thermal Energy
Chemical energy changes into thermal energy when something burns.
Electrical energy changes into thermal energy when a wire that is carrying an electric current gets hot.
Thermal energy can be transformed into radiant energy such as when a bar of metal is heated to a high temperature, it glows and gives off light.