1. Energy- Topic14 (I.) Forms of energy (see video “forms of energy” on my website) kinetic energy- the energy of motion thermal energy- all objects store thermal energy the higher the temperature, the more thermal energy light energy sound energy elastic potential energy- when a springy material stretches or compresses (a bungee cord, bow and arrow nuclear energy- energy stored in the nucleus of an atom (this powers the sun, nuclear power plants, bombs) gravitational potential energy- objects gain gravitational potential energy when lifted above the ground chemical energy- stored in the bonds of chemicals (ex. Food, fuel like coal) electrical energy – electrons flowing thru a wire

2. Energy- Topic14 (I.) Forms of energy (see video “forms of energy” on my website) kinetic energy- thermal energy- light energy sound energy elastic potential energy- nuclear energy- gravitational potential energy- chemical energy- electrical energy –

3. Energy Demos- Notes Topic14 Alka Seltzer demo: 2 beaker demo:

4. Raquetball demo: Wymhurst Machine: Mass suspended from the ceiling:

5. Silently Read Pages (172 - 178 ) of text Fill out concept chart

6. Topic 14- Energy formulas The two main types of energy we will need to be able to calculate are kinetic energy and gravitational potential energy

7. Kinetic Energy EquationUnits KE = ½mv 2 The Energy of Motion KE = ½(mass)x(velocity) 2 Joules (J) kgm 2 /s 2 If the object is moving it has Kinetic Energy Ask … “Is it moving?”

8. Potential Energy Equation The Energy of Position PE g = mgh PE g =(mass)x(gravity)x(height) Units Joules (J) kgm 2 /s 2 If the object is above the ground it has Potential Energy Ask … “Is it above the ground?”

9. Notes topic 15 Energy can change form

10. Wiley coyote http://bit.ly/pY8h6o http://www.wimp.com/gomachine/ http://www.tokyomango.com/tokyo_mango/ 2007/05/rube_goldberg_m.html http://www.tokyomango.com/tokyo_mango/ 2007/05/rube_goldberg_m.html http://bit.ly/pY8h6o http://www.wimp.com/gomachine/ http://www.tokyomango.com/tokyo_mango/ 2007/05/rube_goldberg_m.html http://www.tokyomango.com/tokyo_mango/ 2007/05/rube_goldberg_m.html http://bit.ly/pY8h6o http://www.wimp.com/gomachine/ http://www.tokyomango.com/tokyo_mango/ 2007/05/rube_goldberg_m.html http://www.tokyomango.com/tokyo_mango/ 2007/05/rube_goldberg_m.html

11. http://www.physicsclassroom.com /mmedia/energy/ce.cfm What do you notice about the green bar?

12. “The Conservation of Energy” The Conservation of Mechanical Energy Kinetic and Potential Energy

13. To identify each type of Mechanical Energy ask the following questions: Kinetic Energy: (KE) – Is the object moving? Gravitational Potential Energy: (PE g ) – Is the object above the ground? Elastic Potential Energy: (PE e ) – Is a spring compressed or an elastic stretched out?

14. Note: Point 1 is the highest and Point 2 and 4 are “on the ground” Look at the rollercoaster below.- Question 1  Identify if the rollercoaster car has Gravitational Potential Energy, Kinetic Energy or both at each point.

15. Note: Point 1 is the highest and Point 2 and 4 are “on the ground” Look at the rollercoaster below.  Identify if the rollercoaster car has Gravitational Potential Energy, Kinetic Energy or both at each point.  Fill in the table identifying the amount of kinetic and potential energy for each point. PE g KE KE + PE g KE KE + PE g

16. Point 1Point 2Point 3Point 4Point 5 PE g 750 J600 J KE400 J ME Question2

17. Point 1Point 2Point 3Point 4Point 5 PE g 750 J600 J KE400 J ME 0 J 750 J 150 J 350 J0 J 750 J 0 J 750 J

18. Quick Video Clip http://www.teachersdomain.org/asset/mck05 _int_rollercoaster/ http://www.teachersdomain.org/asset/mck05 _int_rollercoaster/

19. The Law of the Conservation of Mechanical Energy – Topic 15 states that Energy can convert from one form to another form but in the absence of friction total ME stays same!

20. Identify the types of Mechanical Energy the object has at each point.

21. PE g (above the ground) KE (moving) PE g (above the ground) KE (moving) KE (moving)

22. Conservation of Mechanical Energy In the absence of friction, in a closed system the total mechanical energy (sum of the potential and kinetic energy) remains constant.

23. Energy transformation of a downhill skier http://www.physicsclassroom.com/mmedia/e nergy/se.cfm http://www.physicsclassroom.com/mmedia/e nergy/se.cfm

24. Problem #4  An 18 kg rock falls from a height of 5.0 m. What is the gravitational potential energy it has initially?

25. Problem #5 Assignment #13  An 18 kg rock falls from a height of 5.0 m. What is the gravitational potential energy and the kinetic energy when it is 2.5m above the ground?

26. Problem #6  The same 18 kg rock falls from a height of 5.0 m. What is the kinetic energy it has as it hits the ground?

27. The Law of the Conservation of Mechanical Energy Pendulum “bob” http://www.physicsclassroom.com/mmedia/energy/pe.cfm Animation of a pendulum

29. The Law of the Conservation of Mechanical Energy Pendulum “bob” Mechanical Energy is conserved when no dissipative forces are present. Total mechanical energy stays the same as long as there is no friction! PEg KE KE + PEg PEg = 500J

30. Pendulum animated http://www.physicsclassroom.com/mmedia/e nergy/pe.cfm http://www.physicsclassroom.com/mmedia/e nergy/pe.cfm

31. Problem #1  Calculate the potential energy of the 10kg rock at the top of a 20m high cliff.  What is the kinetic energy of the rock at the bottom of the cliff?

32. Problem #1  Calculate the potential energy of the 10kg rock at the top of a 20m high cliff.  What is the kinetic energy of the rock at the bottom of the cliff right before it hits the ground? PE = ? m = 50kg h = 30m PE KE PE = mgh PE = (10kg)(9.8m/s 2 )(20m) PE = 1960 J ME top = ME bottom PE top = KE bottom 1960J = KE =1960J

33. Problem #2  Calculate the kinetic energy of the 10kg person moving at 5m/s at the bottom of a hill.  What is the potential energy of the person at the top of the hill?

34. Problem #2  Calculate the kinetic energy of the 10kg person moving at 5m/s at the bottom of a hill.  What is the potential energy of the person when they come to rest at the top of the hill? KE PE KE = ? m = 10kg v = 5m/s KE = ½mv 2 KE = ½ (10kg)(5m/s) 2 KE = 125 J ME top = ME bottom KE bottom = PE top 125J = PE =125J

35. Law of conservation of mechanical energy In the absence of friction, in a closed system the total mechanical energy (sum of the potential and kinetic energy) remains constant.