1. Energy Chapter 16.1 As the roller coaster zooms up and down the track, the energy changes btwn kinetic and potential energy.

2. Energy Energy comes in many different forms: –potential energy –kinetic energy –solar energy –nuclear energy

3. Uses of Energy We use energy everyday: –to cook –run vehicles –keep buildings warm/cool –communicate –to run the miniature factories (cells) in our bodies What is energy?

4. Vocabulary Word energy: the ability to do work or produce heat kinetic energy (KE = 1/2mv 2 ) energy of motion potential energy (GPE = mgh) energy of position or composition

5. Energy is Conserved As water runs through the turbines of the hydroelectric plant, some of the potential energy is converted into electrical energy

6. Energy is Conserved As wood burns in a fire, some of its potential energy is released as heat

7. Energy is Conserved Energy is always changing forms, but the total amount of energy does NOT change. Energy is conserved.

8. Vocabulary Word Law of conservation of energy: in any chemical reaction or physical process energy is neither created nor destroyed (though it may change from one form to another).

9. Chemical Potential Energy Chemical potential energy is energy stored in a substance because of its composition (position of its electrons). octane (C 8 H 18 ) is a component of gasoline

10. Chemical Potential Energy potential energy in octane is from the arrangement and strength of the bonds as octane burns, some of the energy is converted to work to move the pistons and some is converted to heat.

11. Vocabulary Word heat (q): energy flows from a warmer object to a cooler object

12. Heat The warmer object gets cooler The cooler object gets warmer They will both continue to transfer heat until both reach the same temperature

13. Vocabulary Word calorie: the amount of heat required to increase the temperature of pure water by 1 o C Calorie: nutritional Calorie is equal to 1000 calories or 1kcal

14. Vocabulary Word joule: the SI unit for heat. 1 joule is equal to 0.2390 calories. 1 calorie is equal to 4.184 joules

15. Specific Heat Since 1 calorie (or 4.184 joules) is the amount of heat to increase the temperature of water by 1 o C, the specific heat of water is 4.184 joules

16. Specific Heat Different substances have different specific heats Some substances require less energy to heat up (gold) and others require a lot (water)

17. Water Water has a very high specific heat. Large bodies of water (lakes, oceans...) can absorb and release large amounts of heat, that’s why the climate near a large body of water is more stable.

18. Vocabulary Word specific heat: the amount of heat required to raise the temperature of 1 gram of a substance by 1 o C

19. Heat Absorbed or Released The amount of heat absorbed or released by a substance can be calculated using the following formula: q = c x m x  T heat = specific heat x mass in grams x change in temperature

20. Energy The sun is an inexhaustible source of energy. Why can’t the solar energy meet all our energy needs?

21. Solar Energy Why can’t the solar energy meet all our energy needs? –only available during the day –must be able to store (solar ponds) –sodium sulfate decahydrate pools (dissolve/recrystalize) –photovoltic cells

22. Photovoltic Cells convert solar energy directly into electricity