Lesson 1: Forms of Energy
A. Energy
1. Energy influences everything in your life.
2. Energy is the ability to cause change.
B. Potential Energy
1. Potential energy is stored energy due to the interaction between objects and particles.
2. Objects with potential energy have the possibility to cause change.
3. Any object has gravitational potential energy if it has mass and height aboveEarth’s surface.
4. Chemical energy is energy that is stored in and released in the bonds betweenatoms.
5. Nuclear energy is the energy stored in and released from the nucleus of an atom.
a. The energy released from the Sun comes from nuclear fusion.
b. During nuclear fusion, nuclei of atoms join together and release large amountsof energy.
c. During nuclear fission, the nucleus of an atom breaks apart, and energy is released.
d. Energy used in nuclear power plants to make electricity comes from nuclear fission.
C. Kinetic Energy
1. Kinetic energy is energy due to motion.
2. The kinetic energy of a moving object is related to the mass and the speed of theobject.
a. An object must have mass and speed to have kinetic energy.
b. If two objects have the same mass, the object that moves with greater speed hasgreater kinetic energy.
3. Electric energy is the energy in an electric current.
D. Combined Kinetic Energy and Potential Energy
1. A(n) system is a collection of interacting objects, parts, or ideas that act together asa(n) whole.
2. In science, the environment is anything that is not part of the system.
3. The sum of the potential energy and the kinetic energy in a system is mechanicalenergy.
4. Thermal energy is the sum of the kinetic energy and the potential energy of theparticles that make up an object.
E. Energy Carried by Waves
1. A(n) wave is a disturbance that transfers energy from one place to another withouttransferring matter.
2. Sound energy is energy carried by sound waves, which are waves that move throughmatter.
3. Electromagnetic waves are electric and magnetic waves that move perpendicularly toone another.
a. The energy carried by electromagnetic waves is radiant energy.
b. Electromagnetic waves travel through matter and also through spaces with littleor no matter.
c. Forms of electromagnetic waves include visible light, ultraviolet waves, X-rays,gamma rays, and infrared rays.
Lesson 2: Energy Transfers and Transformations
A. Law of Conservation of Energy
1. The law of conservation of energy states that energy can be transformed from oneform to another, but it can’t be created or destroyed.
2. Energy transfer takes place when energy moves from one object to another withoutchanging form.
3. Energy transformation occurs when one form of energy is converted to anotherform of energy.
4. Work is the transfer of energy that occurs when a(n) force makes an object move inthe direction of the force; work is only being done while the force is acting on theobject.
5. Energy transformations are inefficient because some energy is transformed to a formof energy that is not usable.
6. A system can be open or closed.
a. A(n) open system is a system that exchanges matter or energy with theenvironment.
b. A(n) closed system is a system that does not exchange matter or energy with the environment.
B. Energy Transformations and Electric Energy
1. A(n) renewable energy resource is an energy resource that is replaced as fast as orfaster than it is used.
a. Radiant energy from the Sun, or solar energy, is converted into electric energy insolar cells, also called photovoltaic cells.
b. Solar energy is sometimes transformed into thermal energy, which is used toconvert water to steam; the steam turns a(n) generator, which transformsmechanical energy into electric energy.
c. Wind turbines are built in places where winds blow most of the time.
d. A(n) generator is turned by the turbine, changing kinetic energy of wind toelectric energy.
e. In hydroelectric plants, the mechanical energy of falling water being channeledthrough a turbine is transformed to electric energy.
f. In a(n) geothermal plant, thermal energy from within Earth is transferred towater, creating steam, which is used to turn turbines in electric generators.
g. Burning biomass releases stored chemical energy, which can then be transformedto electric energy.
2. Most energy that we use comes from fossil fuels and nuclear energy.
3. A(n) nonrenewable energy resource is an energy resource that is available in limitedamounts or that is used faster than it can be replaced in nature.
a. Petroleum, natural gas, propane, and coal are fossil fuels.
b. Fossil fuels are a concentrated form of chemical energy that came from plants andanimals that lived millions of years ago.
c. Some energy plants use fission to produce thermal energy.
Lesson 3: Particles in Motion
A. Kinetic Molecular Theory
1. The transfer of thermal energy depends on the movement of particles in the material.
2. The kinetic molecular theory of matter explains how particles move.
a. Particles make up all matter.
b. Particles are in constant, random motion.
c. Particles constantly collide with each other and with the walls of their container.
3. Temperature is the measure of the average kinetic energy of the particles ina material.
a. If the particles in a material have little kinetic energy, the material feels cold.
b. The SI unit for temperature is kelvin (K).
c. Another temperature unit often used by scientists is Celsius (°C).
4. Thermal expansion is the increase in volume that a material undergoes when itstemperature increases.
a. At higher temperatures, the particles in matter move faster, requiring morevolume because they collide more often, pushing each other apart.
b. Thermal contraction is the decrease in a material’s volume when its temperature decreases.
5. Kinetic energy is transferred from one material to another one when their particlescollide.
6. Heat is the movement of thermal energy from a region of higher temperature toa region of lower temperature.
7. Materials are said to be in thermal equilibrium when the temperatures of materialsthat are touching are equal.
B. Heat Transfer
1. Conduction is the transfer of thermal energy due to collisions between particles inmatter.
2. Radiation is the transfer of thermal energy by electromagnetic waves.
3. Convection is the transfer of thermal energy by the movement of the particles fromone part of a material to another.
C. Heat and Changes of State
1. When thermal energy is added to solid ice, its temperature increases until it startsto melt, changing to liquid water.
2. When thermal energy is removed from liquid water, its temperature decreases until it starts to freeze, changing to solid ice.
3. When thermal energy is added to liquid water, its temperature increases until itstarts to vaporize, changing to a(n) gas.
4. When thermal energy is removed from a gas, it changes to a(n) liquid througha process called condensation.
5. Sublimation occurs when a solid absorbs energy and changes directly to a gaswithout first becoming a(n) liquid.
6. Deposition occurs when a gas changes directly to a solid without first becominga(n) liquid.
D. Conductors and Insulators
1. Thermal energy moves quickly in a thermal conductor.
2. Thermal energy moves slowly in a thermal insulator.
Content Practice B (page 14)
1. O
2. J
3. E
4. F
5. J
6. N
7. D
8. C
9. I
10. L
11. F
12. E
13. E
14. B
15. D
16. H
17. K
School to Home (page 15)
1. Possible answers: a. The energy stored inobjects due to their mass and their heightabove Earth’s surface; b. The books on my
bookshelf have gravitational potential energy.
2. Possible answers: a. Energy that is stored inand released in the bonds between atoms;b. The food I had for breakfast has chemical
energy stored in its chemical bonds.
3. Possible answers: a. The energy in an electriccurrent; b. I use electric energy to power myalarm clock.
4. Possible answers: a. The sum of the potentialenergy and the kinetic energy in a system;b. I have mechanical energy when I pick upa ball and throw it to a friend.
5. Possible answers: a. The sum of the kineticand potential energy of the particles thatmake up an object; b. The hot chocolate I had
for breakfast had thermal energy.
6. Possible answers: a. The energy carried bysound waves; b. My alarm clock wakes meusing sound energy.
7. Possible answers: a. The energy carried byelectromagnetic waves; b. The radiant energyfrom the Sun lit my bedroom this morning.
Key Concept Builder (page 17)
1. T
2. F; potential
3. F; mass
4. F; chemical energy
5. T
6. F; nuclear fusion
7. F; are in motion
8. F; speed
9. T
10. T
11. F; the environment
12. T
13. F; chemical
Key Concept Builder (page 18)
1. potential
2. system
3. system
4. environment
5. system
6. environment
7. mechanical
8. potential
9. atoms
10. particles
11. particles
12. kinetic
13. thermal
14. potential
15. potential
16. thermal
17. potential
18. thermal
19. potential
20. thermal
Content Practice B (page 33)
1. F; conservation of energy
2. T
3. F; energy transfer
4. T
5. T
6. F; inefficient
7. F; an open
8. F; a renewable
9. T
10. F; kinetic
11. T
12. F; renewable
Math Skills (page 34)
1. 1.8 J
2. 54.6 J
3. 34.125 J
4. 3.5 m
Key Concept Builder (page 38)
Accept thermal energy as part of each transfer andtransformation.
1. transferred; mechanical energy
2. transformed; chemical energy to mechanicalenergy
3. transformed; chemical energy to mechanicalenergy and sound energy
4. transformed; chemical energy to mechanicalenergy
5. transformed; electric energy to radiant energy
6. transferred; mechanical energy
7. transformed; chemical energy to mechanicalenergy and sound energy
8. transformed; electric energy to sound energy
Key Concept Builder (page 39)
1. A resource replaced as fast as or faster than itis used.
2. solar, wind, hydroelectric, geothermal, biomass
3. mechanical energy transformed to electricenergy by falling water
4. chemical energy to electric energy, thermalenergy, and radiant energy
5. a limited resource or a resource used fasterthan it can be replaced in nature
6. petroleum, natural gas, coal, propane, uranium
7. chemical energy
8. (possible answers) harmful wastes such assulfur dioxide, acid rain, and radioactivewaste; damaging to the environment
Content Vocabulary (page 46)
1. equilibrium
2. sublime
3. vaporization
4. thermal insulator
5. radiation
6. thermal conductor
7. Conduction
8. heat
9. convection
10. temperature
Content Practice A (page 50)
1. The temperature must increase.
2. They contract.
3. It decreases.
4. particles
5. collisions between particles
6. radiation
7. movement of particles
8. (possible answers): gas to liquid(condensation); gas to solid (deposition)
9. a slow speed
Key Concept Builder (page 55)
1. particles
2. Celsius (°C)
3. thermal energy
4. thermal expansion
5. temperatures
6. thermal contraction
7. water
8. particles, motion, container
9. dense
10. volume, temperatures
11. volume
Key Concept Builder (page 56)
1. kinetic energy
2. faster
3. thermal equilibrium
4. decreases
5. bottle
6. increases
7. increases
8. glass
9. apart
Key Concept Builder (page 57)
1. the transfer of thermal energy due to collisionsbetween particles in matter
2. from the flame to the water; from the handleto the hand
3. the transfer of thermal energy by the movementof particles from one part of the material toanother
4. throughout the water
5. the transfer of thermal energy byelectromagnetic waves
6. from the flame to the air; from the hot waterto the air