What is Energy?

1. What is Energy?

2. Nature of Energy • Energy- Ability to cause change. • Anytime change occurs, energy is transferred from one object to another • Ex: leaves moving and sunlight warming an object

3. Nature of Energy • Energy is the ability to cause change or to do work. (joules) • Energy that is released causes change and does work. • When work is done on something, Energy is added to it. • Energy is contained in everything. • All matter contains energy. • Non-matter such as light contains energy.

4. Power • Power is the rate at which energy is transferred. • Power = Energy Transferred Time

5. Energy of Motion • Kinetic Energy- Energy an object has due to its motion • If an object isn’t moving, it doesn’t have kinetic energy • Kinetic energy increases as an object moves faster • Kinetic energy increases as the mass of an object increases

6. Kinetic Energy • Kinetic Energy = ½ X Mass X Velocity² • ↑ Mass = ↑ Kinetic Energy • ↑ Velocity = ↑ Kinetic Energy • Velocity = speed in a given direction

7. Energy of Position • Object can have energy even though it is not moving • Potential Energy-The energy stored in an object because of its position. • Depends on position (ex: high or low) and mass (more mass, more potential energy)

8. Gravitational Potential Energy • Gravitational Potential Energy = Weight x Height • ↑ Weight = ↑ Potential Energy • ↑ Height = ↑ Potential Energy

9. Forms of Energy • Mechanical Energy • Thermal Energy • Electrical Energy • Chemical Energy • Nuclear Energy • Electromagnetic Energy

10. Forms of Energy • Mechanical Energy- associated with the position and motion of an object. • Ex: Throwing a football • Potential + Kinetic

11. Forms of Energy Thermal Energy- Sum of kinetic and potential energy of the particles in a material. • Ex: Chemical reactions occur inside your cells that produce thermal energy (released by chemical reactions from chemical energy)

12. Forms of Energy Chemical Energy-Energy stored in chemical bonds. When chemical bonds are broken and new chemicals are formed, some of the energy is released. • Ex: Food contains chemical energy used to produce energy for our bodies

13. Forms of Energy Electromagnetic Energy- Energy carried by light. • When light is absorbed by an object it becomes warmer • Objects absorbs energy from the light and then becomes thermal energy

14. Forms of Energy Electric Energy-Energy carried by electric currents. • Ex: Used by appliances to function

15. Forms of Energy Nuclear Energy-Energy that is stored in the nucleus of an atom. • Nuclear power plants are complex plants that transform nuclear energy into electric energy

16. Energy Transformations • Energy can be transformed or changed from one form of energy to another. • Food is chemical energy that is transformed by our bodies into thermal energy, electrical energy, and mechanical energy. • Gasoline is chemical energy that is transformed by our car engines into mechanical energy and thermal energy

17. Conservation of Energy • The Law of Conservation of Energy-states that energy is never created or destroyed. • Energy can only be transformed or changed from one form to another. • Energy also can be transformed into matter and matter can be transformed into energy.

18. The Energy Conversion Cycle

19. The Source of Energy • All of the energy in the universe now is the same amount that has always been there and it is the only amount that will ever be there. • The surface of the Earth receives most of its energy from the Sun and a little from radioactive atoms that are inside the Earth.

20. The Source of Energy • Fossil Fuels such as coal, oil, and natural gas were formed from the remains of plants and animals that lived millions of years ago. (Think about what are Fossils) • Because Fossil fuels are being used up much faster than they can be replaced, they are called Nonrenewable Resources. • The source of fossil fuels originates with the Sun.

21. The Source of Energy • Nuclear Energy is energy that is released when the nuclei of uranium atoms are broken apart. • Because the forces that hold atoms together are so strong, enormous amounts of energy are released when atoms are broken apart. • Nuclear Energy is a nonrenewable resource.

22. The Source of Energy • Hydroelectric, Geothermal, Wind, Wave, and Solar Energy are all Renewable Energy Sources. • Renewable energy sources are not likely to be used up by people because the available supply does not decrease.