2. Nature of Energy Pgs. 402 - 414

3. The Mysterious Everything What is this stuff? Whatever happens is caused by it. Whatever is, is made up of it. You need it, you are made up of it. Everything needs it. Everything is it. It is everything! You need it to run, to walk, to sit, to think, to sleep, "perchance to dream", to eat, "perchance to belch." You use it constantly, every moment, awake or asleep. You can't get mad without it. You can't get glad without it You can't get anything without it. It makes the wind blow, rain fall and lightning zap and thunder. It "feeds" volcanoes and earthquakes. It drives tidal waves, typhoons, and tornadoes. It powers the universe! It is the Mysterious Everything. Let's call it ME for short. WHAT IS THIS STUFF?

4. What is energy?  Energy is the ability to do work or cause change  Work happens when a force moves an object through a distance  Force is a push or pull  Work can also be thought of as the transfer of energy. A joule is the metric unit used for energy and work!

5. Transferring Energy  Everything around you has energy.  You notice energy when a change takes place.  Anytime a change occurs, energy is transferred from one object to another.

6. Transfer of Energy Examples  Someone’s foot hits the floor and you hear a sound.  The top of your desk becomes warm when the sun shines on it.  A CD player is plugged up and turned on. The CD turns, and you hear music. 3 energy transfers have occurred. Electrical -  Mechanical  Sound

7. Kinetic Energy  2 kinds of energy  Kinetic energy (energy being transferred)  Potential energy (energy being stored)  Kinetic energy is energy in motion  An object’s kinetic energy depends on its mass and velocity  Mass – amount of matter in an object  Velocity – speed in a given direction

8. Kinetic energy needs mass & velocity?  If the mass of an object increases, its kinetic energy increases.  If the velocity of an object increases, its kinetic energy increases.  All energy and work are measured in joules. Marble Experiment

9. Calculating Kinetic Energy Kinetic Energy = Mass x Velocity 2 2 3 x 9 = 27 = 13.5 joules 2 2 2 2 Plug in the following values and see how kinetic energy changes. Mass = 3, velocity = 6 Mass = 6, velocity = 3

10.  CHECKPOINT   Which has the greatest kinetic energy: a motorcycle moving at 30 km/hour, a four- door car moving at 30 km/hour, or a truck sitting on top of a hill?

11. Potential Energy  Energy that is stored and NOT IN MOTION  2 types of potential energy  Elastic potential energy – potential energy associated with objects that can be stretched or compressed  Gravitational potential energy – potential energy associated with height Elastic Potential Energy

12.  CHECKPOINT   What is the unit for work and energy? Joule or Newton-meter

13. Calculating Gravitational Potential Energy  GPE = weight x height (unit is joules)  The greater the weight of an object or the greater the height it is lifted, the greater is its GPE  If you don’t have weight but have the mass, you must multiply the mass by 9.8 m/s 2 in order to convert it to the weight in newtons.

14.  CHECKPOINT   Describe how the ball experiment is an example of gravitational potential energy.

15. Let’s Review!

16. Different Forms of Energy 1.Mechanical Energy 2.Thermal Energy 3.Chemical Energy 4.Electrical Energy 5.Electromagnetic Energy 6.Nuclear Energy

17.  Energy transformations occur constantly all around you.  Many machines are devices that transform energy from one form to another. Example: An automobile engine transforms the chemical energy in gasoline into energy of motion.

18. Mechanical Energy  Energy associated with the motion or position of an object  Can be potential or kinetic

19. Thermal Energy  Energy of particles in an object  When particles move faster, more heat is generated  When particles move slower, less heat is generated Food Coloring Experiment

20. HOW THERMAL ENERGY MOVES  Thermal energy only moves from something warm to something cool. Example: Hot chocolate’s thermal energy moves from the cup to the cooler spoon and to the cooler air around it.

21. Chemical Energy  Potential energy stored in chemical bonds that hold chemical compounds together

22.  In your body, the transformation of chemical to kinetic energy occurs in muscle cells.

23. Electrical Energy  Moving electric charges producing electricity

24. Generating Electrical Energy  The enormous amount of electrical energy that is used everyday is generated by power plants.  Every power plant works on the same principle---energy is used to turn a large generator.

25.  A generator is a device that transforms kinetic energy into electrical energy.  In fossil fuel power plants, coal, oil, or natural gas is burned to boil water.  As the hot water boils, steam rushes through a turbine, a device which contains a set of narrowly spaced fan blades. The steam pushes on the fan blades and turns the turbine. The turbine, in turn, rotates a shaft in the generator to produce electricity.

26. Electromagnetic Energy  Has both electric properties and magnetic properties  Travels in waves and includes microwaves, ultraviolet radiation, infrared radiation, and visible light

27. Nuclear Energy  Type of potential energy stored in the nucleus of an atom  One type of nuclear energy is called nuclear fission (nucleus splits apart)  Another type of nuclear energy is called nuclear fusion (many nuclei fuse together) Nuclear fission Nuclear fusion