Energy Conversions

1. Energy Conversions Chapter 9 Section 2

2. Where does energy come from? How does energy get from one place to another? • Energy comes in many forms and is often converted numerous times before it reaches our homes, schools, and places of work. • To scientists, conservation of energy is not saving energy.

3. Conversion vs. conservation • Conversion- to change. In this unit we are typically changing energy • Conservation- to save. Every day usage is to save water or fuel by not using as much. Science law usage- When we say energy is conserved we mean that it is not lost, all of the energy that goes into a chemical reaction or energy conversion can be accounted for. Not all of it can be used, ( heat, sound and random vibrations can be difficult to use) but it is all there. Energy is not gained or lost in a conversion.

4. What is Energy Conversions? • The law of conservation of energy says that energy is neither created nor destroyed. • When we use energy it doesn’t disappear. We change it from one form of energy into another. • An Energy transfer often leads to a energy conversion. • Energy conversion is a change from one form of energy into another.

5. Energy Transformations • http://www.youtube.com/watch?v=MIqSg4JSJt8 • What are some of the energy transformations you saw in the video? Please raise your hand.

6. Conversions Involving Chemical Energy • Your body performs energy conversions • What did you have for breakfast? • As your body digests food, chemical energy is released and is available to you. • ===== Chemical energy of food is converted into kinetic energy when you are active and thermal and thermal energy to maintain body temperature.

7. The chemical energy in the food you eat is a result of suns energy. • When we eat fruits, vegetables, grains, you are taking in chemical energy that resulted from a chemical change involving the suns energy. • Photosynthesis uses light energy to produce new substances with chemical energy.

8. Conversions Involving Electrical Energy • We use electrical energy all the time. • iPod, radio, toaster, T.V., cell phone. Examples of Conversions Involving Electrical Energy Describe an example in which electrical energy is converted into thermal energy.

9. Energy and Machines • Another way to learn about energy is to look at how machines use energy. • The machine can make work easier by changing the size or direction of the force required to force required to do the work.

10. Example: • Using a nutcracker, you transfer your energy to the nutcracker and it transfers energy to the nut. But the nutcracker will not transfer more energy to the nutcracker than you put into it. • Some of the kinetic energy you transfer to a nutcracker is converted into sound energy as the nutcracker transfers energy to the nut. • What are other machines we use, and what type of energy does it transfer? Figure 19 (pg. 226)

11. Some machines are especially useful because they are energy converters. • These machines are specifically designed to convert energy from one from to another. • What are some other machines that convert Energy? Figure 21 (pg. 227)

12. To scientists, conservation of energy is not saving energy. The law of conservation of energy says that energy is neither created nor destroyed. When we use energy it doesn’t disappear. We change it from one form of energy into another.