1. Energy

2. Energy & Work Closely related Energy: ability to do work Work: transfer of energy Both measured in Joules

3. Energy Types 1.Kinetic Energy: Energy in motion 2.Potential Energy: Stored energy (not moving) depends on position or condition of object

4. Examples of KE

5. Calculating KE KE = ½ mv 2 m = mass v = velocity Which increases kinetic energy more: doubling the mass or doubling the velocity?

6. Examples of PE Firecracker Boulder on top of cliff battery

7. Elastic Energy (type of potential energy) Energy stored in a compressed material –Example: rubber band, spring

8. Gravitational PE PE that depends on object’s height, and weight G.P.E. = mgh m = mass g = 9.8 m/s 2 h= height. Which will have greater GPE: a rock on a 3 story ledge or a rock on a 20 story ledge?

9. Forms of Energy Mechanical Energy: Related to motion of objects –Ex : moving machine parts Windmill Engine piston

10. Mechanical Energy PE Converts to KE and vice versa Mechanical Energy = KE + PE –Total energy Skier Roller Coaster Dart

11. Thermal Energy Related to heat Thermal Energy = total KE and PE of all particles in an object –Particles in matter are constantly moving

12. Chemical Energy (type of potential energy) Energy stored in chemical bonds within a substance Ex: Gas, food, human body, battery

13. Electrical Energy Energy of Electric Charges

14. Electromagnetic Energy Energy traveling in the form of waves X-rays Visible light

15. Nuclear Energy Energy stored in nucleus of an atom Nuclear Power plants convert nuclear energy to electricity

16. Energy conversions Law of conservation of energy: Energy cannot be created or destroyed, only converted from one form to another

17. Impact crater in Arizona formed within past 20 yrs Large KE of meteor converted to large amount of thermal energy vaporizing everything in Close proximity

18. Energy conversions Light bulb : converts electrical into thermal and electromagnetic energy Compressed Spring: converts potential to kinetic Burning wood: stored chemical energy converted to thermal and electromagnetic

19. If friction is ignored total mechanical energy will remain constant (KE + PE) start = (KE + PE) end Pendulum would swing forever!!! Energy Conversion in a Pendulum

20. Viewing a Pendulum Pendulum Energy Conversion