1. Energy: Forms and Changes

2. Forms of Energy  The main forms of energy are: Thermal(Heat) Chemical Electromagnetic(light) Nuclear Mechanical(motion) Electrical Sound

3. Energy Transformations or Conversions  Most forms of energy can be transformed into other forms.  A change from one form of energy to another is called an energy transformation.

4. Transformations Between Potential and Kinetic Energy  One of the most common energy transformations is the transformation between potential energy and kinetic energy.  In waterfalls such as Niagara Falls, potential energy is transformed to kinetic energy.  The water at the top of the falls has gravitational potential energy.  As the water plunges, its velocity increases.  Its potential energy becomes kinetic energy.

5. Kinetic-Potential Energy Conversion Roller coasters work because of the energy that is built into the system. Initially, the cars are pulled mechanically up the tallest hill, giving them a great deal of potential energy. From that point, the conversion between potential and kinetic energy powers the cars throughout the entire ride.

6. Kinetic vs. Potential Energy At the point of maximum potential energy, the car has minimum kinetic energy.

7. Common Energy Transformations Every day, energy transformations are all around you. Some of these transformations happen inside you!

11. Energy and Friction So what happens to the energy of the top? As the top spins, it encounters friction with the floor and friction from the air.  Whenever a moving object experiences friction, some of its kinetic energy is transformed into thermal energy. (Why you cannot have perpetual motion machines)  So, the mechanical energy of the spinning top is transformed to thermal energy.  The top slows and eventually falls on its side, but its energy is not destroyed—it is transformed.

12. Conservation of Energy  If you set a spinning top in motion, will the top remain in motion forever?  No, it will not.  Then what happens to its energy?  Is the energy destroyed?  Again, the answer is no.  The law of conservation of energy states: Energy is not created nor destroyed only changed into other forms. The total amount of energy remains the same.

13.  What happens when electrical energy is changed to thermal energy? a.An energy transfer takes place. b.A force change takes place. c.An energy conversion takes place. d.An electrical conversion takes place.

14.  What happens when electrical energy is changed to thermal energy? a.An energy transfer takes place. b.A force change takes place. c. An energy conversion takes place. d.An electrical conversion takes place.

15. Any time an energy conversion takes place, some of the original energy is converted to which one of the following? a.sound energy b.potential energy c.light energy d.thermal energy

16. Any time an energy conversion takes place, some of the original energy is converted to which one of the following? a.sound energy b.potential energy c.light energy d.thermal energy

17. When you eat fruits and vegetables, which of the following types of energy are you taking in? a. thermal energyc.electrical energy b.sound energyd.chemical energy

18. When you eat fruits and vegetables, which of the following types of energy are you taking in? a. thermal energyc.electrical energy b.sound energyd.chemical energy

19. Which of the following is a conversion from light energy to chemical energy? a.turning on a stove to heat dinner b.turning on a lamp c.growing an apple tree d.making toast in a toaster

20. Which of the following is a conversion from light energy to chemical energy? a.turning on a stove to heat dinner b.turning on a lamp c.growing an apple tree d.making toast in a toaster