1. Energy and Energy Resources
What is energy?

2. Energy and Work: Working Together
Energy- the ability to do work
When one object does work on another object, energy is transferred from the first object to the second object.
The unit for energy is Joule (J)– just like work.
Energy and Work: Working Together
How big (or small) is a Joule?
There are J in a calorie
Your food Calories are actually kcal—1000 calories!
A 2000kcal diet would be Joules!

3. Types of Energy Mechanical energy Kinetic Potential Thermal energy
Chemical energy
Electrical energy
Electromagnetic energy
Nuclear energy

4. Mechanical Energy
Mechanical Energy- the total energy of motion and position of an object.
Both kinetic and potential energy are kinds of mechanical energy
Mechanical Energy (ME) = potential energy + kinetic energy
(J) (J) (J)

5. Calculating Mechanical Energy
What is the mechanical energy of a book being held in the air that has 100 J or potential energy and 50 J of kinetic energy?
What is the potential energy of a goose that has 60 J of kinetic energy and a total mechanical energy of 135 J?

6. Kinetic Energy Kinetic Energy- energy in motion
All moving objects have kinetic energy
Kinetic Energy = KE = mv2 2
m = mass (Kg) v = m/s KE= joules
Velocity has a greater effect on kinetic energy than mass does (because it’s squared)
So if you double mass _______________ KE
If you double the velocity_____________KE
If you triple the mass ________________KE
If you triple the velocity______________KE

7. Kinetic Energy Calculations
What is the kinetic energy of a car that has a mass of 1,200 Kg and is moving at a speed of 20 m/s?
What is the kinetic energy of a car that has a mass of 2,400 kg and is moving at 20 m/s? How does this kinetic energy of the car in the above example compare?
A 50 kg cheetah has a KE of 18,000J. How fast is the cheetah running?

8. Potential Energy
Potential Energy- The energy that an object has because of the position, shape, or condition of the object
Gravitational Potential Energy - When you lift an object, you do work on it. When you do this, you transfer energy to the object and give the object gravitational potential energy.
energy stored as a result of position or height.
GPE = weight x height
GPE = Joules (J) Weight = Newtons (N) height = meters (m)
Remember –> Weight = mass x gravity
So GPE = m x g x h or GPE = weight x height

9. Potential Energy

10. Potential Energy Calculations
What is the gravitational potential energy of a book with a weight of 13 N at a height of 1.5 m off the ground?
What is the gravitational potential energy of a cat that weighs 40 N standing on a table that is 0.8 m above the ground?
What is the gravitational potential energy of a diver with a mass 51 Kg standing on a platform that is 10 m above the ground?

11. Types of Energy

12. Forms of Energy Nonrenewable Resources
Fossil Fuels-Oil and natural gas, as well as coal, are the most common fossil fuels. All fossil fuels contain stored energy from the sun which can be converted into other kinds of energy.
Burning coal is a common way to generate electrical energy.
Petroleum is used to make gasoline, wax, and plastics.
Natural gas is often used in home heating.
The United States’ primary source of electrical energy is generated by burning fossil fuels.

13. Creating the energy we use
How do we make electricity from these resources?
Electric generators convert the chemical energy in fossil fuels into electrical energy by the process shown below.
An electric generator converts energy of one type into another type of energy.

14. Forms of Energy
Nonrenewable Resources cont’d
_____________The energy that comes from the nucleus of an atom.
Nuclear fission is a process of releasing energy through splitting nuclei apart.
Nuclear Fusion releases energy when a less massive nuclei combine to form a more massive nucleus.

15. Forms of Energy Renewable Resources
Solar -Sunlight can be changed into electrical energy through solar cells.
Hydroelectric -The potential energy of water in a reservoir can be changed into kinetic energy as the water flows through a dam.

16. Forms of Energy Renewable Resources Cont’d
Wind - A wind turbine changes the kinetic energy of the air into electrical energy by turning a generator.
Biomass- Plants use and store energy from the sun. Organic matter, such as plants, wood, and waste that can be burned to release energy.
Geothermal- Thermal energy caused by the heating of Earth’s crust is called geothermal energy. Some geothermal power plants pump water underground next to hot rock. The water returns to the surface as steam, which can then turn the turbine of a generator.

17. Other Forms of Energy
Thermal energy is all of the kinetic energy due to random motion of the particles that make up an object.
Chemical Energy-The energy in a compound that changes as its atoms are rearranged

18. Others Forms of Energy
Electrical Energy is the energy of moving electrons.
(negatively charged particles in atoms)
Sound Energy -is caused by an object’s vibrations.
Light Energy Produced by the vibrations of electrically charged particles.

19. Energy Conversions Law of Conservation of Energy
Energy can not be created or destroyed.
Energy can be converted from one form to another.
Any form of energy can change into any other form of energy.
In energy conversions, some energy is always lost as heat (Thermal energy).
After energy conversions, you always end up with the same total amount of energy as the original amount of potential energy.

20. Where Does Energy go? 3: Conservation of Energy
Friction-A force that opposes motion between two surfaces that are touching
Energy Efficiency - is a comparison of the amount of energy before a conversion with the amount of useful energy after a conversion
More efficient = less friction/less lost energy

21. Perpetual Motion
A machine that will run forever without any additional energy
The machine will put out exactly as much energy as it takes in.
This is impossible because waste thermal energy always occurs due to friction.