1. ENERGY THE DRIVING FORCE

2. What is Energy? The ability to do workThe ability to do work The ability to cause changeThe ability to cause change Force is a push or pullForce is a push or pull Measured in Joules, Joules = kg●(m/s) 2Measured in Joules, Joules = kg●(m/s) 2 Formula: E = KE + PEFormula: E = KE + PE E =.5mv 2 + ma grav h (KE =.5 x mv 2 ) ( PE = ma grav h)

3. Energy is Conserved (in a closed system) https://www.youtube.com/watch?v=- p3msL1P8bwhttps://www.youtube.com/watch?v=- p3msL1P8bw

4. Different Forms of Energy 6 different types :6 different types : MechanicalMechanical Thermal EnergyThermal Energy Chemical EnergyChemical Energy Electrical EnergyElectrical Energy Electromagnetic EnergyElectromagnetic Energy Nuclear EnergyNuclear Energy

5. Forms of Energy Mechanical EnergyMechanical Energy Describes energy stored and released according to function or forceDescribes energy stored and released according to function or force

6. Forms of Energy Thermal EnergyThermal Energy Heat in all its forms and flowsHeat in all its forms and flows

7. Forms of Energy Chemical EnergyChemical Energy Stored and released in the bonds between atomsStored and released in the bonds between atoms

8. Forms of Energy Electric EnergyElectric Energy Energy that is caused by moving electric charges Since the electric charges are moving, this is a form of kinetic energy.

9. Forms of Energy Electromagnetic EnergyElectromagnetic Energy Waves of mostly invisible energyWaves of mostly invisible energy Includes light, radio waves, X-raysIncludes light, radio waves, X-rays

10. Forms of Energy Nuclear EnergyNuclear Energy Stored and released from the nucleus of an atomStored and released from the nucleus of an atom

11. Two descriptions of Energy Potential Energy - Energy stored by position or conditionPotential Energy - Energy stored by position or condition Kinetic Energy - Released energy or energy of motionKinetic Energy - Released energy or energy of motion

12. Potential Energy The easiest quantified PE is Gravitational PEThe easiest quantified PE is Gravitational PE This is the PE stored in an object by its height above another reference pointThis is the PE stored in an object by its height above another reference point PE Grav = m a grav hPE Grav = m a grav h Joules = kg●(m/s) 2 Remember, a grav = 9.8 m/s 2

13. Potential Energy, revisited… Another form is Elastic PEAnother form is Elastic PE This is the PE stored in an object by its being disturbed from is natural state,This is the PE stored in an object by its being disturbed from is natural state, and how much it wants to return to that natural stateand how much it wants to return to that natural state Good examples:Good examples: Springs, swings, pendulums, rubber bandsSprings, swings, pendulums, rubber bands

14. Potential Energy, revisited… Another form is Chemical PEAnother form is Chemical PE This is the PE stored in an object by the chemical bonds between its atoms and moleculesThis is the PE stored in an object by the chemical bonds between its atoms and molecules The energy is released when the chemicals react and form new bondsThe energy is released when the chemicals react and form new bonds Good examples:Good examples: Burning a log, firecrackers,Burning a log, firecrackers,

15. Kinetic Energy This is the KE released by an object by its motionThis is the KE released by an object by its motion KE = ½ m v 2KE = ½ m v 2 Joules = kg●(m/s) 2Joules = kg●(m/s) 2

16. Potential or Kinetic? On the next few slides, tell whether the energy is potential or kinetic…On the next few slides, tell whether the energy is potential or kinetic…

17. A bowling ball rolling down the lane 1.Potential 2.Kinetic

18. A sandwich 1.Potential 2.Kinetic

19. A ball being thrown through the air in a projectile path 1.Potential 2.Kinetic

20. A gallon of gasoline 1.Potential 2.Kinetic

21. A lawnmower burning a gallon of gasoline 1.Potential 2.Kinetic

22. Law of Conservation of Energy Energy can not be created or destroyed in normal reactionsEnergy can not be created or destroyed in normal reactions Energy can be changed from one form to anotherEnergy can be changed from one form to another The total amount of energy must be the same before and after a change in energyThe total amount of energy must be the same before and after a change in energy

24. Mechanical Energy in a Pendulum

25. Which of these describes Energy? 1.Ability to do work 2.Ability to cause change 3.Ability to increase energy 4.Ability to decrease work

26. At which point is PE at maximum? 1.A 2.B 3.C 4.D

27. Joules is not the unit for which of these? 1.Potential Energy 2.Kinetic Energy 3.Work 4.Force

28. At which point is KE at maximum? 1.A 2.B 3.C 4.D