1. D57 Conservation of Energy

2. D57 Conservation Background
Energy makes everything happen, and we…
notice energy when its released or absorbed.
Define “release” and “absorb”.
Examining energy as it changes led to one of the most important ideas in science.
COPY CHALLENGE QUESTIONS
AND GIVE EXAMPLES OF EACH:
What is a law?
What is a scientific law?

3. Release & Absorb Energy
Energy often seems used up but is really either transferred and/or transformed to other types.
Define “transfer” and “transform”.
Like food energy provides thermal energy for us.
Energies can also “chain” together and change from one type to a second type and then a third.
Plants use sunlight energy (photosynthesis) and food energy, decay into oil, then chemical energy from oil transforms into motion energy for cars.

4. Law of Conservation of Energy
Light energy from a bulb is less than electrical energy going in. Where is the “lost energy”?
Energy is not lost or missing but transformed into energy not recognized or useful. Most lightbulbs also give off heat energy too.
Total energy is the same before and after a transformation. Energy can be transferred or transformed, but cannot be lost or destroyed.

5. D57 Process of Heating
Thermal (heat) energy is usually released in an energy transformation.
Heating is often useful, but not always.
This thermal energy is not lost or destroyed but is usually dissipated, or spread out.
This makes it hard to capture or transform into other more useful types of energy.

6. D57 Energy Efficiency-A
EFFICIENCY is the ratio of useful energy that is released to the total energy absorbed.
No energy transformation is 100% useful.
A car’s engine transforms chemical potential energy of gasoline into other types of energy:
74% turns into heat
23% used by friction
Only 3% is used to move the car!

7. D57 Energy Efficiency-B The government EPA rates appliance efficiency
Energy Efficient means it uses less energy (an Energy Star) than a similar model.
By using less energy to do the same work, an Energy Star appliance increases efficiency.

8. D57 Energy Conservation Energy Conservation = reduce or save energy
Like turning off lights helps use less energy, or conserves energy, when lights are not needed.
Or use an energy efficient device that uses less energy whenever you turn it on, like LED bulbs
Energy efficiency saves resources, reduces pollution, and saves money. This is a major goal of technology and engineering.

9. D57 Conservation Analysis: Date_____ Name______________________ Hr__
Answer questions using complete paragraphs.
What choice a or b shows Law of Conservation of Energy for a toaster? Pick one and Explain.
Electrical energy into heat, light, and sound, OR
Chemical potential energy into heat and light
Explain if a generator makes electricity by using the Law of Conservation of Energy.
If you drop a ball it does not bounce as high as it started. Explain where the energy went.

10. D57 Conservation Analysis: Date_____ Name______________________ Hr__
Answer questions using complete paragraphs.
What choice a or b shows Law of Conservation of Energy for a toaster? Pick one and Explain.
Electrical energy into heat, light, and sound, OR
Chemical potential energy into heat and light
Explain if a generator makes electricity by using the Law of Conservation of Energy.
If you drop a ball it does not bounce as high as it started. Explain where the energy went.