1. P.S. 1: Chapter 5: Energy

2. I. The Nature of Energy A. What is Energy?
-Every change that occurs—large or small—involves energy

3. --energy-- the ability to do work & cause change
1.) Energy & Work
--energy-- the ability to do work & cause change
- When something is able to change its environment or itself, it has energy!
Bill Nye - Energy

4. 2.) Different Forms of Energy
KINETIC
*Motion
POTENTIAL
*Elastic
*Chemical
*Gravitational

5. B. Kinetic Energy
--kinetic energy-- the energy a moving object has because of its motion
-The kinetic energy of a moving object depends on the object’s mass and its speed
-UNIT USED = Joule (J)

6. C. Potential Energy
-Even motionless objects can have energy  “unseen” energy
--potential energy-- stored energy due to position

7. 1.) Elastic Potential Energy
--elastic potential energy-- energy stored by something that can stretch or compress
- Stored energy of position is converted to energy of motion

8. Bill Nye (again) Energy

9. 2.) Chemical Potential Energy
--chemical potential energy-- energy stored in chemical bonds
-When bonds are broken through chemical reactions  energy is released

10. 3.) Gravitational Potential Energy
--gravitational potential energy-- energy stored by objects due to their position above Earth’s surface
REMEMBER: acceleration of gravity on Earth = 9.8 m/s2

11. 4.) Changing GPE
-The GPE of an object can be increased by increasing its height above the ground
-If two objects are at the same height the object with the larger mass has more gravitational potential energy

12. II. Conservation of Energy
A. Changing Forms of Energy
1.) Transforming Electrical Energy
Lightbulbs  transform electrical energy into light so you can see

13. …some of that electrical energy transformed into thermal energy  heat you can feel

14. 2.) Transforming Chemical Energy
-CAR fuel  spark plug fires  chemical potential energy converts into thermal energy
hot gases expand thermal energy is converted into kinetic energy

15. B. Conversion Between Kinetic & Potential Energy
--mechanical energy-- the total amount of potential and kinetic energy in a system
mechanical energy = potential energy + kinetic energy
RoadRunner & Coyote Physics

16. 1.) Falling Objects
Apple on a tree gravitational potential energy
Apple comes loose accelerates due to gravity
As it falls loses height gravitational potential energy decreases

17. -Potential energy transformed into kinetic energy as velocity of the apple increases
NOTE: mechanical energy of the apple doesn’t change as it falls

18. -Potential energy that the apple loses gained back as kinetic energy…
…total amount of energy remains the same!
The Story of Kinetic and Potential Energy

19. 2.) Energy Transformations in Projectile Motion
-Energy transformations also occur in an object traveling in a curved path  during projectile motion

20. NOTE: mechanical energy of the ball remains constant as it rises and falls

21. 3.) Energy Transformations in a Swing
-Ride starts with a push that gets you moving kinetic energy
As swing rises you lose speed but gain height

22. TRANSLATION: Kinetic Energy changes to Gravitational Potential Energy!
-At the top of your path potential energy is at its greatest…
…as the swing accelerates downward PE changes to KE

24. C. Law of Conservation of Energy
Law of Conservation of Energy: Energy cannot be created or destroyed (only converted from one form to another)
Rube Goldberg Machines - Japan TV

25. - Energy transformation is at times difficult to see in some systems but it does occur!
Honda Rube Goldberg Commercial - Physics in Action

26. 1.) The Effect of Friction
-Swing example  you can’t swing forever- without a push or you pumping your legs back & forth- you will eventually come to a stop Kinetic Energy lost??????

27. NO!!! Swing’s ropes/chains rub on their hooks...air pushes on the rider
Some mechanical energy of swing converted to thermal energy

28. 2.) Converting Mass Into Energy  FUSION & FISSION
-Small amount of mass is transformed into a large amount of energy
FUSION  small particles collide to make a larger particle
Nuclear Fusion Animation

29. FISSION  large particles break apart to become smaller particles
Fission Animation