1. Chapter 13
Energy

2. 13.1 What is Energy
Energy - The ability to do work or cause change (such as moving an object some distance)
Work is the transfer of energy.
Energy is measured in Joules
Power is the rate at which energy is transferred (converted from one form to another) or the amount of energy transferred in a unit of time.
Chapter 13

3. 13.1 What is Energy Power = Energy transferred / Time Review
Power - The rate at which work is done
power = work/time power = force x distance/time
power units = J/sec = Watts (W)
Chapter 13

4. 13.1 What is Energy
Two basic kinds of energy: kinetic energy and potential energy
Kinetic energy (KE) - energy of motion (kinetos)
KE = 1/2 mass x velocity2
Potential energy (PE) - stored energy due to position or shape of an object (gravitational or spring)
Gravitational Potential Energy = work done to lift the object
Chapter 13

5. 13.1 What is Energy Remember: Work = Force X Distance
Gravitational potential energy = Weight X Height
(Weight is a Force = Mass X Acceleration)
Therefore PEG = mass x acceleration due to gravity (9.8 m/sec2) x height
Elastic potential energy – Energy associated with objects that are stretched or compressed
Chapter 13

6. 13.2 Forms of Energy
Mechanical Energy – The form of energy associated with the position and motion of an object
Mechanical Energy = Potential energy + Kinetic energy
Chapter 13

7. 13.2 Forms of Energy
Forms of energy associated with the particles of objects include thermal energy, electrical energy, chemical energy, nuclear energy, and electromagnetic energy.
Chapter 13

8. 13.2 Forms of Energy
Thermal energy – heat – The total potential and kinetic energy of the particles in an object
Electrical energy – electricity – The energy of electric charges
Chapter 13

9. 13.2 Forms of Energy
Chemical energy - chemical reaction/bonds – The potential energy stored in the chemical bonds that hold compounds together
Nuclear energy – fission & fusion – The potential energy stored in the nucleus of an atom
Chapter 13

10. 13.2 Forms of Energy
Electromagnetic energy - light, radiation – Travels in waves which have some electrical and magnetic properties
Chapter 13

11. 13.3 Energy Transformations and Conservation
Most forms of energy can be transformed into other forms.
energy transformation- the process of changing one form of energy into another
One of the most common energy transformations is the transformation between potential energy and kinetic energy.
Chapter 13

12. match - mechanical  thermal  chemical  thermal  light
body - convert chemical energy in food to mechanical energy to move muscles
match - mechanical  thermal  chemical  thermal  light
Book examples - waterfall, juggling, pole vault, pendulum
The law of conservation of energy – According to the law of conservation of energy, energy cannot be created or destroyed. The total amount of energy is the same before and after any transformation.
Chapter 13

13. friction - converts mechanical to thermal energy, reduces efficiency
Chapter 13

14. Energy and Matter - Einstein’s theory of relativity
Matter can be transformed to energy.
Matter is anything that has mass and takes up space.
Therefore, matter and energy together are always conserved.
Chapter 13

15. 13.4 Energy conversions and fossil fuels
Formed from the remains of ancient plants and animals that lived 400 million years ago.
Coal, petroleum, natural gas - chemical potential energy
Fossil fuels - contain energy that came from the sun.
Energy conversions pg. 464 – Flowchart
Chapter 13

16. 13.4 Energy conversions and fossil fuels
Fossil fuels can be burned to release the (potential) chemical energy stored millions of years ago.
Combustion – The process of burning fuels
Non-Renewable Energy
Chapter 13

17. Chapter 13 Vocabulary Energy Kinetic energy Potential energy
Gravitational potential energy
Elastic potential energy
Mechanical energy
Thermal energy
Electrical energy
Chapter 13

18. Chapter 13 Vocabulary Chemical energy Nuclear Energy
Electromagnetic energy
Energy transformation
Law of conservation of energy
Matter
Fossil fuels
Combustion
Chapter 13