1. Energy Conversion & Conservation
Kim Lachler
Updated 2015
NCES: 6.P.1

2. Energy Conversion
the change from one form of energy to another

3. Energy Conversion Chemical energy
We get our energy from chemical energy
How_Our_Bodies_Use_Energy.mov How_Does_Food_Supply_Energy_.mov
Remember plants get their energy from the sun; light energy
By using photosynthesis they convert light energy into sugar- stored energy – potential energy
We eat the plants or animals that eat the plants = potential energy for us
We either store this energy- in fat – potential energy or use the energy to move – kinetic energy

4. Energy Conversion
Calorie – how we measure the potential energy in food
calorie = 4.2 Kilojoules

5. Energy Conversion
A piece of buttered toast contains about 315 kilojoules of energy
Jog for 6 minutes
Bicycle for 10 minutes
Walk briskly for 15 minutes
Sleep for 1 ½ hours

6. Energy Conversion
Machines can convert energy to make it into forms useful for us.
Alarm clock – electrical energy  light and sound energy
Battery – chemical energy  electrical energy
Light bulb – electrical energy  light and thermal energy

7. Energy Conservation
Any time energy is converted from one form to another, thermal energy is given off.

8. Energy Conservation
Remember things move from potential energy to kinetic energy and back again.
As this happens some of the energy is converted to thermal energy, so the potential energy becomes less and less.

9. Energy Conservation Energy is converted to thermal energy by friction
Friction – a force that opposes motion between two surfaces that are in contact

10. Law of conservation of energy
energy can not be created or destroyed but can be changed from one form to another

11. Law of conservation of energy
Closed system
Where you can measure all the different energies from start to finish of an action.
The original potential energy = all the final energies
mechanical energy ( potential + kinetic)
sound energy
thermal energy

12. Perpetual Motion
Perpetual motion – a machine that would run forever without any additional energy
No, because of friction.
Is this possible?

13. Energy Efficient
comparison of the amount of energy before a conversion with the amount of useful energy after a conversion.
Some machines are not energy efficient – transferring most of the energy to a form you don’t want.

14. Energy Efficient
Car engine convert only 25% of the gasoline to kinetic energy, the rest is converted to thermal energy as a result of friction.

15. Energy Efficient
To help keep machines efficient
oil
aerodynamic

16. Bibliography
Holt,Rinehart and Winsteon, North Carolina Holt Science & Technology, Holt,Rinehart and Winsteon, New York, 2005
Discovery Education, accessed 12/28/2010
What is a pendulum anyway?, accessed 12/28/2010