Chapter 9

1. Chapter 9 Energy and Energy Resources

2. Kinetic and Potential Energy 9:1

3. Terms • Energy- the ability to do work • Unit: joules (J) • Work- involves a transfer of energy and occurs when a force causes an object to move in the direction of the force ( work = force x distance) • Unit: joules (J)

4. Kinetic Energy • energy of motion • All moving objects have kinetic energy • Kinetic energy depends on speed and mass K.E. = m v2 2 • K.E. = kinetic energy m = mass v = velocity • faster objects — more kinetic energy • objects with more mass — more kinetic energy

5. Try This • What is the kinetic energy of a turtle with a mass of .9 kg moving at .05 m/s? 2. What is the kinetic energy of a 6,400 kg tractor trailer traveling at 25m/s?

6. Potential Energy • energy an object has because of its position or shape. • Example: stretching a rubber band changes its shape. This gives it elastic potential energy. • Gravitational potential energy- energy an object has due to its position above the Earth's surface. • Example: lifting up the rubber band gives it G.P.E. • Depends on the height and the weight of an object • G.P.E. = weight x height

7. Mechanical Energy • the total energy of motion and position of an object. M.E. = P.E. + K.E • M.E. = mechanical energy • P.E. = potential energy • K.E. = kinetic energy • Mechanical Energy can be all potential energy, all kinetic energy or part potential and part kinetic energy

8. Forms of Energy 9:1 continued

9. Thermal Energy Thermal Energy- total energy of particles that make up an object. • Particles at higher temperatures have more thermal energy(because they are moving faster) than the same number and kind of particles at a lower temperature • Increasing the number of particles you have in an object increases the thermal energy • Mostly kinetic energy • Examples: stove, heater, Atlantic Ocean, curling iron, furnaces, etc.

10. Chemical Energy Chemical Energy- energy of a compound that changes as its atoms are rearranged to form new compounds • Much potential energy stored in chemical bonds • Potential energy is converted to kinetic energy during the chemical reaction • Examples: food, carbohydrates, gasoline, kerosene, butane, firewood, etc.

11. Electrical Energy Electrical Energy- energy of moving electrons • Mostly kinetic energy • Examples: TV, VCR, flashlight, computer, calculator, & anything electrical or battery operated

12. Sound Energy Sound Energy- caused by vibrations of an object • Potential energy is converted into kinetic energy • Potential energy- example: stretching the string of a guitar • Kinetic energy- the string moving and vibrations occurring in the air • Examples: speakers, singing, musical instruments, sonar, ultrasounds, taping on a desk, etc.

13. Light Energy Light Energy- produced by the vibrations of electrically charged particles • Mostly kinetic energy • Electromagnetic radiation • Examples: radio waves, visible light, radar, microwaves, infrared radiation, UV rays, x-rays, gamma rays, etc.

14. Nuclear Energy Nuclear Energy- the energy associated with the changes in the nucleus of an atom (the nuclei split or join together) • Potential energy is converted into kinetic energy • Potential Energy stored in the nucleus of an atom • Kinetic Energy when the nucleus is split (fission) or joins with other nuclei (fusion) • Examples: nuclear fusion in stars and in the sun, nuclear fission at a nuclear power plant, nuclear bombs, some types of radiation therapy, radioactive decay,

15. Energy Conversions 9:2

16. Terms Energy Conversion • A change from one form of energy into another Energy Efficiency • A comparison with the amount of energy before a conversion with the amount of useful energy after a conversion

17. From Kinetic to Potential and Back

18. Conversions Involving Chemical Energy