Chapter 3 Energy

1. Chapter 3 Energy 3.1 Energy Exists in Different Forms 3.2 Energy Can Change Forms But is Never Lost 3.3 Technology improves the ways people use Energy

2. 3.1 Energy exists in different forms • Different Forms of Energy have different uses • Electrical energy ----- used in all appliances • Energy from sun------ used by plants to grow • Energy from food-----used by us to move

3. 3.1 Energy exists in different forms • B. Six Forms of Energy • 1. Mechanical energy a) Def: Energy that moves an object, it causes movement b) Examples: Carry book Frog Dancing electrons moving in a wire (electricity)

4. 3.1 Energy exists in different forms B. Six Forms of Energy 2. Sound • Def: Sound travels in air particles as vibrations • Ex: music, hitting a pencil on a table

5. 3.1 Energy exists in different forms B. Six Forms of Energy 3. Chemical • Def: the energy stored in chemical composition of matter. • Examples • Food • Fire Cracker • Battery

6. 3.1 Energy exists in different forms B. Six Forms of Energy 4. Thermal Energy • Def: energy from the movement of particles in a matter • All objects have thermal energy • Example • Ice cream melting gains thermal energy • Water freezing looses thermal energy

7. 3.1 Energy exists in different forms B. Six Forms of Energy 5. Electromagnetic Energy a)Def: Energy that travels in wavesthrough space b) Examples • UV Rays • Microwaves • X-rays • Sun light

8. 3.1 Energy exists in different forms B. Six Forms of Energy 6. Nuclear Energy a)Def: Energy stored in the nucleus of an atom from fission or fusion b) Examples • Sun • Nuclear Power Plant

9. 3.1 Energy exists in different forms • C. Kinetic Energy (KE) • Def: Energy in motion; any moving thing has k-energy • If mass increases, KE increases • If speed increases, KE increase For example, if a small marble and a large bowling ball are rolling at the same speed, the bowling ball has more kinetic energy because it has more mass.

10. 3.1 Energy exists in different forms • D. Potential Energy (PE) • Def: stored energy due to location or composition • Gravity causes an object to have PE due to its position above the ground • Energy in food is potential energy

11. 3.1 CW - Review • List 3 ways you use energy. How does each example involve change. • What are some changes that can be caused by sound energy? • What are some changes that can be caused by electromagnetic energy? • What two factors determine an objects kinetic energy? • Describe a stone falling off a tabletop in terms of both kinetic energy and potential energy.

12. Chapter 3 Energy 3.1 Energy Exists in Different Forms 3.2 Energy Can Change Forms But is Never Lost 3.3 Technology improves the ways people use Energy

13. 3.2 Energy can change forms but is never lost • Energy changes forms • Ex: Plants change sunlight (electromagnetic energy) to sugar (chemical energy) then we eat the sugar and change it to heat(thermal) and motion(mechanical).

14. PE KE PE KE PE 3.2 Energy can change forms but is never lost • Energy changes forms • 2. PE turns into KE • he is at the top, this position gives him PE, but he is not moving, so no KE • As he moves down the hill his PE turns into KE • at the bottom of the hill his position does not give him PE, but he is moving fast, so he has KE

15. 3.2 Energy can change forms but is never lost • Energy changes forms • 3. Ex: water and a dam • 1st: water behind dam is high: PE • 2nd: Water falls through pipe: PEKE • 3rd: moving water moves turbine: KEKE • 4th: moving turbine turns generator: • KEKE • 5th:Moving generator makes electricity: • KE  Electricity

16. PE KE PE KE PE 3.2 Energy can change forms but is never lost Energy changes forms Classwork Draw your own picture or comic showing at least 4 changes in energy

17. 3.2 Energy can change forms but is never lost

18. 3.2 Energy can change forms but is never lost • B. Energy is always conserved: • The law of conservation of energy states that energy can neither be created nor destroyed. • The amount of energy you start out with is the same amount of energy you end up with.  • Only the forms of energy change

19. 3.2 Energy can change forms but is never lost Heat waste • C. Energy conversions may produce unwanted forms of energy • Energy efficiency is the amount of useful energy you get from a system. • most energy transformations are not very efficient • Energy can be wasted, usually as heat. • Ex: a car engine changes chemical energy to motion(KE) but a lot is wasted as heat • Ex: efficient light bulbs waste less heat Movement

20. 3.2 Energy can change forms but is never lost • Conservation of Energy; Energy Efficiency CW • 3.2 Challenge and Extension • 3.2 Reinforcing Key Concepts

21. Chapter 3 Energy 3.1 Energy Exists in Different Forms 3.2 Energy Can Change Forms But is Never Lost 3.3 Technology improves the ways people use Energy

22. 3.3 Technology improves the ways people use energy • Technology improves energy conversions. • Efficient lights • LED (light – emitting diode) converts all of the electrical energy into light, so it is more efficient • Efficient Cars • Cars use fuel injectors to control the amount of gas fed into the engine, so no gas is wasted • Hybrid cars use both gasoline and electrical energy from batteries to waste less heat

23. 3.3 Technology improves the ways people use energy • B. Technology improves the use of energy resources. • Today solar and wind energies are used to produce electricity. • Sunlight is changed into electric energy by solar cells. • Wind is also used to produce electricity at wind farms.