1. Chapter 9: Energy and Energy Resources
What is Energy?

2. Energy EQ’s
What is the relationship between potential and kinetic energy?
What are the characteristics of the different forms of energy?
How does the Law of Conservation of Energy relate to the energy transformations?

3. How does ENERGY and WORK, work together?
Energy: Ability to do work. Objects can GAIN energy by work being done on them. Objects can TRANSFER energy by doing work, which is the same as CONVERTING energy from one form to another. Energy is measured in joules.
How does ENERGY and WORK, work together?
Work is a transfer of energy….
WHEN WORK IS DONE…..
THE SAME AMOUNT OF ENERGY IS INVOLVED.

4. Forms of Energy:
Kinetic
Potential
Mechanical
Thermal
Chemical
Electrical
Sound
Light
Nuclear

5. Kinetic vs Potential Energy
Kinetic: The Energy of MOTION
Potential: The Energy of POSITION
All moving objects have kinetic energy
Doesn’t involve motion
EVERYTHING has POTENTIAL ENERGY….even if it is still….
Kinetic energy DEPENDS on SPEED and MASS
Gravitational Potential Energy DEPENDS on WEIGHT and HEIGHT
Kinetic Energy = MV² / 2
Gravitational Potential Energy =
W x H
M= Mass (kg) V= Speed (m/s)
W= weight (Newton) H= height (meters)
More MASS = More Kinetic Energy
More SPEED = More Kinetic Energy
SPEED has a GREATER effect on Kinetic Energy…. WHY????
More WEIGHT = More Potential Energy
More HEIGHT = More Potential Energy
MV² / 2 = Joules
W x H = Joules

6. Mechanical Energy = potential energy + kinetic energy
Total energy of motion and position of an object
Mechanical Energy = potential energy + kinetic energy
Potential Energy
Kinetic Energy
So…. What happens to the kinetic energy if your potential energy decreases?
*It increases!

7. Thermal Energy: all of the kinetic energy due to random motion of the particles that make up and object.
The faster particles move the more Kinetic energy…. If they are moving faster then the particles have more space….
Temperature is the measure of the average kinetic energy of the particles in motion in an object

8. C H E M I A L N R G Y
Chemical Energy is POTIENTIAL ENERGY…
This energy is required to bond atoms together.
Example: Your body breaks the chemical bonds in food to provide energy to YOU!

9. Electrical energy: the energy of moving electrons
Electrical energy is POTENTIAL (atoms-electrons) Energy… and Kinetic Energy.
SOUND Energy: Caused by an objects vibration. A form of Potential and Kinetic energy. Example: Guitar; The strings store potential energy, once released, the strings move back to the position--- kinetic

10. Light Energy: Is produced by the vibrations of electrically charged particle.
Nuclear Energy: The change in the nucleus
of the atom.
Produced in 2 ways:
Fusion: when 2 or more nuclei join
together
Fission: when the nucleus splits apart

11. Chapter 9
Energy Conversions

12. Law of Conservation of Energy: energy can be converted from one form to another, but it is neither created nor destroyed.

13. An energy conversion is a change from one form of energy to another
Often one form of energy changes into more than one other form
Some of the original energy gets converted into thermal energy through friction

14. Elastic potential energy: is the kind of potential energy stored in a rubber band or spring; when the rubber band is stretched, or wound-up, or the spring is stretched and let go, the stored energy becomes kinetic energy
Chemical energy: the energy stored in a substance because of its composition
(ex: plants, gasoline)
plays an important role in chemical reactions

15. Mechanical Energy Conversions

16. Energy Resources
Energy resource: is a natural resource that can be converted into other form of energy in order to do useful work
2 types:
Nonrenewable: resources that cannot be replaced, or are replaced much more slowly than they are used
Renewable: resources that are naturally replaced more quickly than they are used

17. Nonrenewable Resources:
Fossil fuels are energy resources formed from the buried remains of animals and plants
Coal
Petroleum
Natural gas
All fossil fuels contain stored energy from the sun which can be converted into other kinds of energy

18. Electric generators convert the chemical energy in the fossil fuels into electrical energy that can be used everyday
Nuclear energy is generated from radioactive elements such as Uranium

19. Renewable Resources:
Solar energy: sunlight is converted into electrical energy through solar cells
Water energy: sun evaporates the water, it falls again as rain and flows through rivers; the potential energy of water in a reservoir can be changed into kinetic energy as the water flows through a dam (hydroelectric power)
Wind energy: caused by the uneven heating of the Earth’s surface, the kinetic energy of wind turns the blades of windmill

20. Geothermal energy is thermal energy caused by the heating of the Earth’s crust; water is pumped underground next to hot rocks, released as steam and turns the turbines of generators
Biomass is stored energy from the sun in organic matter , such as plants, wood, and waste, that can be burned to release energy

21. Energy Resource Advantages Disadvantages
Fossil fuels
• provide a large amount of thermal energy per unit of mass
• are easy to get and transport
• can be used to generate electricity and to make products such as plastic
• are nonrenewable
• produce smog
• release substances that can cause acid precipitation
• create a risk of oil spills
Nuclear 
• is a very concentrated form of energy
• does not produce air pollution
• produces radioactive waste
• is nonrenewable
Solar
• is an almost limitless source of energy
• does not produce pollution
• is expensive to use for large-scale energy production
• is practical only in sunny areas

22. Energy Resource Advantages Disadvantages
Water
• is renewable
• does not produce air pollution
• requires dams, which disrupt a river’s ecosystem
• is available only where there are rivers
Wind
• is relatively inexpensive to generate
• is practical only in windy areas
Geothermal 
• is an almost limitless source of energy
• power plants require little land
• is practical only in areas near hot spots
• produces wastewater, which can damage soil
Biomass
• is inexpensive
• requires large areas of farmland
• produces smoke

23. Chapter 10: Heat and Heat Technology
Temperature

24. Thermal Energy
A. Temperature & Heat
1. Temperature is the measure of the average kinetic energy of the particles in a substance.

25. SI unit for temp. is the Kelvin
(but you will see Celsius used)
a. K = oC (10oC = 283K)
b. oC = K – 273 (10K = -263oC)
3. Thermal Energy – the total of all the kinetic and potential energy of all the particles in a substance.

26. Temperature Conversions
Converting Fahrenheit to Celsius:
(°F-32)x(5/9)=°C
Converting Celsius to Fahrenheit:
(°C x (9/5))+32=°F
Measuring Temperature
Thermal expansion is the increase in volume of a substance because of an increase in temperature, this occurs inside a thermometer
Absolute zero is the lowest temperature on the Kelvin scale and the temperature at which all molecular motion stops

27. Thermal Expansion
Expansion joints keep segments of a bridge apart so that they have room to expand, when the weather is hot, without breaking
Bimetallic strips are two different metals that are bound together, they expand at different rates when heated, used as a switch in a thermostat
Hot air balloons are able to rise because when gases (air) are heated they expand due to the increase in kinetic energy and becomes less dense than the air outside the balloon

29. 4. Thermal energy relationships
a. As temperature increases, so does thermal energy (because the kinetic energy of the particles increased).
b. Even if the temperature doesn’t change, the thermal energy in a more massive substance is higher (because it is a total measure of energy).

30. a. The flow of thermal energy from one object to another.
Cup gets cooler while hand gets warmer
5. Heat
a. The flow of thermal energy from one object to another.
b. Heat always flows from warmer to cooler objects.
Ice gets warmer while hand gets cooler

31. Heat Transfer Heat flows from hot to cold.
If you hold something cold, heat flows from hand to object.
If you hold something hot, heat flows from object to hand
Thermal Conduction- transfer of thermal energy through matter by the direct contact of particles
Occurs because particles are in constant motion
KE transferred as particles collide

33. Conduction Heating of metal pan-
Particles in handle of pan move slowly
Fast moving particles from the bottom bump into slower particles and speed them up
Occurs until all particles move the same speed
Conduction works best in solids- especially metals- because particles are close together

34. Conductors and Insulators
Substances that conduct thermal energy very well are called thermal conductors.
For example, the metal in a doctor’s stethoscope is a conductor. Energy is transferred rapidly from your warm skin to the cool stethoscope. That’s why the stethoscope feels cold.

35. Conductors and Insulators
Substances that do not conduct thermal energy very well are called thermal insulators.
For example, a doctor’s wooden tongue depressor is an insulator. It is at the same temperature as the stethoscope. But the tongue depressor doesn’t feel cold. The reason is that thermal energy is transferred very slowly from your tongue to the wood

36. Conductors and Insulators
Table 1 Conductors and Insulators
Conductors
Insulators
Curling iron 
Flannel shirt
Cookie sheet 
Oven mitt
Iron skillet 
Plastic spatula
Copper pipe 
Fiberglass insulation
Stove coil 
Ceramic bowl

37. Controlling the Flow of Heat
To control the flow of heat: Use clothing, blankets, layers of fat, fur, etc.
Insulator- material that does not allow heat to flow through easily
Gases – like air- are good insulators because:
Gas particles are very far apart & can’t transmit energy through conduction.
If the gas is also held in place, particles can’t move around and warm up the rest of the gas

38. Insulation
Insulation is made of fluffy materials containing pockets of trapped air – prevents heat loss
Thermos- vacuum layer between 2 layers of glass
Vacuum contains few particles so conduction & convection don’t occur.
Thermos- coated in aluminum
Reflects electromagnetic waves that would either heat the substance or allow the substance to cool

39. Picture altered from How stuff works.com

40. Conduction and Convection
Metals- good conductors-because electrons move easily & transfer KE to nearby particles
Fluid- any materials that flows
Convection- transfer of energy in a fluid by the movement of heated particles
Convection currents transfer heat from warmer to cooler parts of a fluid.
Convection vs. Conduction-
Conduction involves collisions and transfers of energy.
Convection involves movement of the energetic particles from one location to another

42. Convection Convection- results in changes in density Lava Lamp-
As particles move faster, they get farther apart
Fluid expands as temperature increases
Larger volume = smaller density
Decreasing density results in the rise of the warmer fluid
Lava Lamp-
Cool oil = dense = sits on the bottom
Warmer oil = less dense than alcohol & rises
As it rises, it loses energy through conduction
Causes decrease in density = sinking

43. Oil starts to lose heat by conduction and falls
Oil is warm, so it rises
When oil is cool

44. Convection Currents
The circular motion of liquids and gases due to density differences that result from temperature differences

45. Radiation Transfer of heat to the earth – occurs through radiation
Radiation- the transfer of energy by electromagnetic waves. The waves travel through space even without matter

46. Heat Transfer on Earth
At equator- earth experiences the most heat from the sun.
Result: evaporation of water and large accumulations of clouds.
As the water vapor rises, it cools and condenses, forming rain
After the rain = dry air
Dry air causes moisture to evaporate, drying out the ground – causes desert
Convection currents create deserts and rain forests over different regions of Earth

47. The Greenhouse Effect
Earth’s atmosphere acts like the windows of a greenhouse by allowing the sun’s visible light to pass through it and traps heat energy due to the greenhouse gases.

48. Land heats up and cools down faster than water
6. Specific Heat
a. Some things heat up or cool down faster than others.
b. thermal conductivity: the rate at which a substance conducts thermal energy
Land heats up and cools down faster than water

49. 1) specific heat of water = 4184 J / kg * oC
c. Specific heat is the amount of heat required to raise the temperature of 1 kg of a material by one degree (C or K).
1) specific heat of water = 4184 J / kg * oC
2) specific heat of sand = 664 J / kg * oC
Heat (J) = specific heat (J/kg*oC) X mass (kg) X change in temperature (oC)
Q = c m T

50. Why does water have such a high specific heat?
water metal
Water molecules form strong bonds with each other; therefore it takes more heat energy to break them. Metals have weak bonds and do not need as much energy to break them.

51. Matter and Heat
Matter consists of particles that can move around at different speeds
States of matter: the physical forms in which a substance can exist
Thermal energy is the total energy of all the particles that make up a substance

52. Matter and Heat
Change of state: is a change of a substance from one state of matter to another (also known as a phase change)
Physical changes (only affects physical properties that do not change the identity of the substance)
Examples: freezing (liquid to solid); melting (solid to liquid); boiling (liquid to gas); condensing (gas to liquid)
There is no change in temperature during a phase change

53. Matter and Heat

54. Matter and Heat
Chemical changes: changes that occur when one or more substances are changed into entirely new substances that have different properties
Thermal energy is added to break chemical bonds and released when new chemical bonds are formed
If more energy is needed to break old bonds than to make new bonds an endothermic reaction has occurred
If more energy is released when making new bonds than needed to break old bonds an exothermic reaction has occurred

55. Endothermic VS Exothermic

56. Food and Chemical Energy
Your body uses energy released from compounds, such as carbohydrates, when broken down in chemical reactions
The Calorie is the unit of energy often used in foods
Can be seen on food nutrition labels
1 Calorie is = 4,184 J
The calorie is also a measure of heat and is measured in a device known as a calorimeter

57. First, mass and temperature of water are measured
d. A calorimeter is used to help measure the specific heat of a substance.
First, mass and temperature of water are measured
T is measured for water to help get its heat gain
This gives the heat lost by the substance

58. Heat Technology
Hot water heating—raises the temperature of water, pumps it through pipes that lead to radiators, radiators heat the cold air
Warm air heating—air is heated by burning fuel in a furnace, the warm air travels through ducts to different rooms, the air heats the room
Solar heating—uses sun’s energy to heat houses and buildings
Passive solar heating system (no moving parts)
Active solar heating system (moving parts)

59. Heat Technology
Heat engines -- machines that transform heat into mechanical energy, or work
Burn fuel through a process called combustion
External combustion engine (burns fuel outside the engine)---steam engine
Internal combustion engine (burns fuel inside the engine)---car engine
Cooling systems---transfer thermal energy out of a particular area so that it feels cooler (an air conditioner)

60. Heat Technology
Heating systems, car engines, and cooling systems all transfer thermal energy to the environment
Thermal pollution is a negative effect
A temperature increase in a body of water that is caused by human activity and that has a harmful effect on water quality and on the ability of that body of water to support life