2. What happens to the gravitation force on an object as it gets closer to another object? Agenda for Monday Nov 10 th 1.Quiz 2.Energy Notes

3. Nature of Energy Energy is all around! – Sound – Light – Wind Living organisms need energy

4. Nature of energy Energy is involved when – A bird flies – A bomb explodes – Rain falls – Electricity flows through a wire

5. Law of Conservation of Energy Energy cannot be created or destroyed – It can only be converted from one form to another 1905, Albert Einstein said mass and energy can be converted into each other – Matter is destroyed, energy is created and vice versa – E = mc 2

6. Nature of energy Energy is the ability to do work – If something does work (exerts a force over a distance) it uses energy Direct connection between energy and work – measured in the same unit: Joules (J)

7. Forms of Energy 5 main categories – Heat – Chemical – Electromagnetic – Nuclear – Mechanical

8. 1. Heat Energy Internal motion of the atoms – Moving particles produce heat Heat energy can be produced by friction Heat energy causes changes in temp. and phase of any form of matter

9. What is the law of conservation of energy? Agenda for Tuesday Nov 11 th 1.Finish notes 2.Problems on GE/KE

10. 2. Chemical Energy Energy that is available for release from chemical reactions. The chemical bonds in a matchstick store energy that is transformed into thermal energy when the match is struck. Fuel and food

11. Examples of Chemical Energy

12. 3. Electromagnetic Energy Gamma rays, x-rays, ultraviolet rays, visible light, infrared rays, microwave and radio bands Power lines carry electromagnetic energy in the form of electricity Light - each color (ROYGBIV) is a different amount of energy

13. 4. Nuclear Energy Nucleus of an atom is the source of nuclear energy SUN – Fission & Fusion

14. 5. Mechanical Energy Energy due to a object’s motion (kinetic) or position (potential) When work is done to an object, it acquires energy When you kick a football, you give mechanical energy to the football to make it move

15. Energy Conversion Energy can be changed from one form to another – Changes in the form of energy are called energy conversions All energy forms can be converted to other forms – Sun through solar cells to electricity – Plants take sun energy to sugars (electromagnetic to chemical)

17. States of Energy Most common energy conversion is between potential and kinetic energy All forms of energy can be in either of 2 states – Potential – Kinetic

18. Kinetic Energy Kinetic Energy – energy of motion – Depends on mass and velocity – Faster an object moves, more kinetic energy it has – Greater the mass, more kinetic energy it has KE – 1/2mv 2 What has a greater affect of kinetic energy, mass or velocity? Why?

19. Potential Energy Potential energy – stored energy – Fuel, nucleus, food – Stored because of the work done on it: Stretching a rubber band Winding a watch Pulling back on a bow’s arrow Lifting a brick high in the air Energy that is stored due to being stretched or compressed is elastic potential energy

20. Gravitational Potential Energy Potential energy that is dependent on height – Waterfall – Suspension Bridge – Falling snowflake GPE = weight x height Or GPE = mgh

21. Gravitational Potential Energy If you stand on a 3 meter diving board, you have 3 times the GPE than you had on a 1 meter diving board

22. Kinetic - Potential Energy Conversions Roller Coaster – Mechanical energy brings them to the top – This gives them great potential energy – Conversion between potential to kinetic energy powers cars through the entire ride At the point of max PE, the car has minimum KE

26. Kinetic - Potential Energy Conversions As a baseball player throws the ball into the air, various energy conversions take place

27. Which has more gravitational potential energy: a ball on a 5 m cliff or a ball on a 10 m cliff? Why? Agenda for Wednesday Nov 12 th 1.Bouncing ball lab All late work due Wednesday Nov 19 th

28. Where is the most kinetic energy? Most potential energy? Agenda for Thursday Nov 13 th 1.KE/GPE Problem set A D C B

29. Equations for Energy

30. Practice Problems 1.A 800g ball is lifted 20 cm. Calculate the potential energy it gains. 2.A man climbs on to a wall that is 3.6m high and gains 2268J of potential energy. What is the mass of the man?

31. 1. Determine the kinetic energy of a 625-kg roller coaster car that is moving with a speed of 18.3 m/s. 2. What is the kinetic energy of a 0.50 kg ball travelling at a speed of 120 m/s ?