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The transparencies in this Prentice Hall Georgia Physical ScienceStandards Review Transparencies book are intended to serve as refreshersof the characteristics of science and content skills covered by the Grade 8Georgia Performance Standards for Science.
The Table of Contents presents a list of the titles of the transparenciesgrouped by standard. The correlation on the pages following the Table ofContents gives a statement of each of the Grade 8 performance standardsand the number of each transparency that reviews that standard.
The art may support the information in the text, relay informationbeyond what appears in the text, or supply data that students can use tointerpret the text or answer the questions. The questions, in turn, aredesigned to take students beyond the material in the review points. Somequestions require an interpretation of the graphic; others give studentsan opportunity to exercise critical-thinking skills.
You can use these transparencies in several ways:
◆ The transparencies lend themselves to whole-class review. You canchoose a standard to focus on, project the related transparency, anddiscuss the topic as a class.
◆ You can leave a transparency projected for a period of time, allowingfor independent review of a particular standard. Students can thenview the transparency at their convenience.
◆ You can arrange for students to view those transparencies that coverstandards of particular concern to them. You may wish to let studentsdecide for themselves which topics they need to review. Or you maychoose to guide them to particular transparencies you think would bemost helpful to them.
However you choose to present them, the transparencies are a valuabletool for reviewing the Georgia Grade 8 Science Performance Standards.
TRANSPARENCY CORRELATION to Georgia Performance Standards
Georgia Performance Standards Transparency
Content Standards
S8P1 Students will examine the scientific view of the nature of matter.
a. Distinguish between atoms and molecules. P12, P13, P14
b. Describe the difference between pure substances (elements and compounds) P15, P16, P17, P18and mixtures.
c. Describe the movement of particles in solids, liquids, gases, and plasma states. P19, P20, P21, P22
d. Distinguish between physical and chemical properties of matter as physical P23, P24, P25 (i.e., density, melting point, boiling point) or chemical (i.e., reactivity,combustibility).
e. Distinguish between changes in matter as physical (i.e., physical change) or P26, P27, P28, P29chemical (development of a gas, formation of precipitate, and change in color).
f. Recognize that there are more than 100 elements and some have similar P30, P31, P32, P33,properties as shown on the Periodic Table of Elements. P34
g. Identify and demonstrate the Law of Conservation of Matter. P35, P36
S8P2 Students will be familiar with the forms and transformations of energy.
a. Explain energy transformations in terms of the Law of Conservation P37, P38of Energy
b. Explain the relationship between potential and kinetic energy. P39, P40
c. Compare and contrast the different forms of energy (heat, light, electricity,mechanical motion, sound) and their characteristics. P41
d. Describe how heat can be transferred through matter by the collisions of P42, P43, P44, P45atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (convection).
TRANSPARENCY CORRELATION to GeorgiaPerformance Standards
S8P3 Students will investigate <the> relationship between force, mass, and
the motion of objects.
a. Determine the relationship between velocity and acceleration. P46, P47, P48,P49, P50, P51
b. Demonstrate the effect of balanced and unbalanced forces on an object in P52, P53, P54, P55,terms of gravity, inertia, and friction. P56, P57, P58, P59,
P60, P61
c. Demonstrate the effect of simple machines (lever, inclined plane, pulley, P62, P63, P64, P65wedge, screw, and wheel and axle) on work.
S8P4 Students will explore the wave nature of sound and electromagnetic radiation.
a. Identify the characteristics of electromagnetic and mechanical waves. P66, P67, P68,
b. Describe how the behavior of light waves is manipulated causing reflection, P69, P70, P71refraction, diffraction, and absorption.
c. Explain how the human eye sees objects and colors in terms of wavelengths. P72, P73
d. Describe how the behavior of waves is affected by medium (such as air, P74, P75water, solids).
e. Relate the properties of sound to everyday experiences. P76, P77, P78
f. Diagram the parts of the wave and explain how the parts are affected by P79, P80, P81changes in amplitude and pitch.
TRANSPARENCY CORRELATION to GeorgiaPerformance Standards
Georgia Performance Standards Transparency
S8P5 Students will recognize characteristics of gravity, electricity, and magnetism as
major kinds of forces acting in nature.
a. Recognize that every object exerts gravitational force on every other object P82, P83, P84and that the force exerted depends on how much mass the objects have and how far apart they are.
b. Demonstrate the advantages and disadvantages of series and parallel circuits P85, P86, P87and how they transfer energy.
c. Investigate and explain that electric currents and magnets can exert force P88, P89, P90, P91on each other.
P1Scientific Habits of MindS8CS1 Students will explore the importance of curiosity, honesty, openness, and skepticism in science and will exhibit these traits in their own efforts to understand how the world works.
Quick Review◆ Scientific investigations include developing a
testable hypothesis, taking accurate measurements,collecting data and observations, and using logicalreasoning to formulate explanations.
◆ Scientific knowledge is constantly reviewed andcritiqued. Scientists should keep clear, honest, andaccurate records of their research so that otherscientists can repeat their experiment and confirmtheir results.
◆ Scientists should be open-minded to new ideas butalso skeptical about information presented withoutevidence.
◆ Not all scientific investigations result in defensibleexplanations. However, even incorrect hypothesesare valuable even if they turn out not to be completely accurate.
Questions
1. Identify the steps in the scientific inquiry process.
2. Why is it important for scientists to keep accurateand clear records of their investigations?
CommunicatePose Questions
Form a Hypothesis
Design an Experiment
Collect and Interpret Data
Draw Conclusions
1. Pose questions, form a hypothesis, design an experiment, collect and interpret data, draw conclusions, communicate2. Clear and accurate records enable other scientists to review and replicate the work.
P3Scientific Habits of MindS8CS3 Students will have the computation and estimation skillsnecessary for analyzing data and following scientific explanations.
Neither Precise nor Accurate Precise but Not Accurate Both Precise and Accurate
Quick Review
◆ Scientists must sometimes rely on estimates whenthey cannot obtain exact numbers.
◆ Accuracy and precision are both important whenyou make measurements.
◆ You may determine an “average” by finding themean, median, or mode.
Questions1. True or false: Estimating is the same as guessing.
2. What does it mean to say a measurement isaccurate?
3. What are the mean, median, and mode of thefollowing set of numbers: 2, 5, 3, 8, 5, 0, 5?
1. False2. It means that the measurement is close to the true or accepted value.3. The mean is 4, the median is 5, and the mode is 5.
P4Scientific Habits of MindS8CS4 Students will use tools and instruments for observing,measuring, and manipulating equipment and materials in scientificactivities utilizing safe laboratory procedures.
Quick Review
◆ Scientists use different tools to gather data. Thesetools can be simple, such as a ruler for measuringthe length of objects.
◆ Scientists often use complex technological tools toanalyze data. Technology helps scientists accessouter space and other remote locations; collect andtreat samples; collect and store data; and measure,compute, and communicate their information.
◆ Computers speed up and extend the scientist’s ability to collect, store, compile, and analyze data.Computers also enable people to organize theirdata and share it with others.
Questions1. What can a computer help a scientist do?
2. Which tool would you use to compare the mass ofdifferent coins?
3. Which tool could you use to collect data about thesounds frogs make?
1. Computers help scientists collect, store, compile, and analyze data. 2. A balance 3. A tape recorder
P9The Nature of ScienceS8CS8 Students will be familiar with the characteristics of scientificknowledge and how it is achieved.
Quick Review◆ Scientists ask and try to answer questions about
the natural world. Although all experiments are different, many follow a similar pattern.
◆ In any scientific investigation, you must identify a testable hypothesis related to the question. Afteridentifying the question and hypothesis, you mustdesign an experiment to test the hypothesis.
◆ Scientific knowledge is sometimes modified as newinformation challenges old theories. A scientifictheory is accepted only when it is supported by alarge body of evidence.
Questions1. Turn this question into a hypothesis: “Which
freezes faster—fresh water or salt water?”
2. In designing an experiment to test this hypothesis,what materials will you need?
1. If I add salt to fresh water, the water will take longer to freeze. 2. Salt, water, containers, and a freezer
Quick Review◆ A physical property of a pure substance is a
characteristic that can be observed without changing it into another substance.
◆ A chemical property is a characteristic of a puresubstance that describes its ability to change intoother substances.
◆ The density of a substance is the same for all samplesof that substance.
Questions1. The two blocks shown have the same volume.
Which one has the greater density?
A. The one with more mass
B. The one with more texture
C. The one with the darker color
D. The one with the lower melting point
2. Is density a physical or chemical property of matter?Explain.
1. A 2. A physical property; It can be observed without changing the substance.
Properties of MatterS8P1.d Distinguish between physical and chemical properties of matteras physical (i.e., density, melting point, boiling point) or chemical (i.e.,reactivity, combustibility).
Quick Review◆ The physical properties of metals include luster,
malleability, ductility, and conductivity.
Questions1. Why do metals tend to have high electrical
conductivity?
2. Which of the following is NOT a physical property of aluminum?
A. high electrical conductivity
B. low thermal conductivity
C. high luster
D. ductility
1. The electrons in a metal can move freely among the atoms. 2. B
Properties of MatterS8P1.d Distinguish between physical and chemical properties of matteras physical (i.e., density, melting point, boiling point) or chemical (i.e.,reactivity, combustibility).
Quick Review◆ Most nonmetals are poor conductors of electric
current and heat. Solid nonmetals are dull and brittle.
Questions1. How do the physical properties of nonmetals
compare with those of metals?
2. Which of the following is a physical property of most nonmetals?
A. high electrical conductivity
B. low thermal conductivity
C. high luster
D. ductility
1. In general, the physical properties of nonmetals are the opposite of those of metals. 2. B
Sulfur crumbles into a powder.
Nonmetals are goodinsulators.
A diver’s tank contains mostly nitrogen and oxygen gas.
Properties of MatterS8P1.d Distinguish between physical and chemical properties of matteras physical (i.e., density, melting point, boiling point) or chemical (i.e.,reactivity, combustibility).
Quick Review◆ A substance that undergoes a physical change is still
the same substance after the change.
◆ Chemical changes produce new substances withproperties different from those of the originalsubstances.
Questions1. Which of the following is a chemical change?
A. boiling water B. baking bread
C. bending metal D. crushing salt
2. The students in the photo mix two unknown liquidsand a solid precipitate forms. What kind of changeoccurred?
1. B 2. Chemical
Physical and Chemical ChangesS8P1.e Distinguish between changes in matter as physical (i.e.,physical change) or chemical (development of a gas, formationof precipitate, and change in color).
Quick Review◆ Chemical changes occur when bonds break and new
bonds form.
Questions1. How many electrons are transferred when a
magnesium atom bonds with an oxygen atom?
A. 1 B. 2
C. 3 D. 4
2. Calcium is in the same group as magnesium. Predictwhat type of bond a calcium atom and an oxygenatom would form.
1. B 2. An ionic bond
A magnesium atom loses two electrons to an oxygen atom. Oppositely charged ions form.
An oxygen molecule has a double bond.
Each oxygen atom can accept two electrons.
An ionic bond forms between the oppositely charged ions.
Bond breaks
Oxygen bonds break.
Magnesium and oxygen combine.
1
2
MgMg + O2–2+
O
+O OO O
Physical and Chemical ChangesS8P1.e Distinguish between changes in matter as physical (i.e.,physical change) or chemical (development of a gas, formation ofprecipitate, and change in color).
Quick Review◆ Chemical reactions are usually exothermic (meaning
they give off heat) or endothermic (meaning theyabsorb heat).
Questions1. Which kind of reaction is taking place when the
airplane burns fuel, endothermic or exothermic?
2. In an exothermic reaction, the total making andbreaking of bonds results in
A. a net absorption of energy.
B. a net release of energy.
C. no energy change.
D. a net loss of mass.
1. Exothermic 2. B
Physical and Chemical ChangesS8P1.e Distinguish between changes in matter as physical (i.e., physicalchange) or chemical (development of a gas, formation of precipitate,and change in color).
Quick Review◆ The graph of an exothermic reaction shows that heat
is released during the reaction.
◆ The graph of an endothermic reaction shows thatheat is absorbed during the reaction.
Questions1. Is the reaction represented by the graph
endothermic or exothermic? Explain how you know.
2. In an endothermic reaction, the total making andbreaking of bonds results in
A. a net absorption of energy.
B. a net release of energy.
C. no energy change.
D. a net loss of mass.
1. Endothermic, because the graph shows that heat is absorbed 2. A
Reaction Energy
Time
Ener
gy
Heatabsorbed
Reactants Products
Activationenergy
Physical and Chemical ChangesS8P1.e Distinguish between changes in matter as physical (i.e., physicalchange) or chemical (development of a gas, formation of precipitate,and change in color).
Quick Review◆ In chemical reactions, the number of atoms stays the
same no matter how they are arranged. So, their totalmass stays the same.
Questions1. What is the mass of iron sulfide produced when
140 g of iron and 80 g of sulfur react?
2. An effervescent tablet is dropped into a beaker ofwater and begins fizzing. The total mass before thereaction is 300 g; the mass after the reaction is 295 g.Why is the mass less after the reaction?
A. Some atoms were destroyed in the reaction.
B. The reaction produced 5 g of gas that drifted away.
C. Chemical reactions always result in a reduction of mass.
D. New atoms were created.
1. 220 g 2. B
FeIron
SSulfur
FeSIron sulfide
�
Conservation of MatterS8P1.g Identify and demonstrate the Law of Conservation of Matter.
Quick Review◆ The Law of Conservation of Matter can be applied to
balancing chemical equations. To describe a reactionaccurately, a chemical equation must show the samenumber of each type of atom on both sides of theequation.
Questions1. Which of the three diagrams represents a balanced
equation, showing conservation of matter?
A. Equation A B. Equation B
C. Equation C D. None of them
2. What type of reaction occurs when hydrogen combines with oxygen to form water — synthesis,decomposition, or replacement?
1. C 2. Synthesis
A �
B �
C �
Hydrogen Oxygen Water
Conservation of MatterS8P1.g Identify and demonstrate the Law of Conservation of Matter.
P38Conservation of EnergyS8P2.a Explain energy transformations in terms of the Law ofConservation of Energy.
Quick Review◆ The Law of Conservation of Energy states that
energy cannot be created or destroyed, but can bechanged from one form into another.
◆ Within any closed system, the amount of energystays constant. In all known processes, some energyis converted to heat.
◆ Matter can change from one state to another ifthermal energy is absorbed or released. For example, absorbing heat can cause a solid to melt.
Questions1. As an ice cube melts, what is the change of state?
What happens to the thermal energy?
2. In the drawing, some of the mechanical energy is notconverted into electrical energy. What happens to it?
3. What other sources of energy can be used to produceelectrical energy?
Discharge
Reservoir
Spillway
Dam
TransformerGenerator
Electromagnet Turbine
1. The ice changes to a liquid. The ice absorbs thermal energy.2. It is converted into thermal energy, which heats the discharged water.3. Fossil fuels, wind, sunlight, and nuclear reactions
The blue skier has more gravitational potential energy because he is at a greater height.
The green skier has more gravitational potential energy because he weighs more.
500 N
500 N 500 N 600 N
Kinetic EnergyS8P2.b Explain the relationship between potential and kinetic energy.
Quick Review◆ Potential energy is stored energy that results from
the position or shape of an object.
◆ There are two types of potential energy.Gravitational potential energy depends on heightand weight. Elastic potential energy is associatedwith stretched or compressed objects.
◆ An object’s gravitational potential energy can becalculated using the formula:
Gravitational potential energy = Weight � Height
Questions1. If the blue skier above is standing at a height of 50
meters above the ground, what is her gravitationalpotential energy?
A. 10 J B. 500 J
C. 2,500 J D. 25,000 J
2. How can you increase the gravitational potentialenergy of a basketball?
1. D 2. By lifting or throwing it higher or by adding to its weight by inserting more air.
Quick Review
◆ Energy comes in many different forms.
◆ Mechanical energy is associated with the positionand motion of an object.
◆ Other forms of energy associated with the particlesof objects include thermal, electrical, chemical,nuclear, and electromagnetic energy.
Questions
1. What form of energy is associated with lightning?
2. Objects with fast-moving atoms and molecules create what form of energy?
P41Forms of EnergyS8P2.c Compare and contrast the different forms of energy (heat, light,electricity, mechanical motion, sound) and their characteristics.
1. Electrical energy 2. Thermal energy 3. Nuclear energy is stored in the nucleus of an atom.
1. Hot air is less dense than cool air.2. Convection currents transfer air heated by the sun throughout the atmosphere.
Baseboardconvector
Pump
Furnace
Burner
Convectioncurrents
Smoke outlet
Quick Review◆ Convection is the process that transfers heat by
the movement of currents within a fluid.
◆ A convection current occurs when a heated fluidrises and is replaced by a cooler fluid.
◆ Convection currents can be used to transfer heatedair throughout a building.
Questions
1. Explain why hot air rises and cool air sinks.
2. Where in nature can you find a large-scale exampleof heating by convection?
Methods of Heat TransferS8P2.d Describe how heat can be transferred through matter by thecollisions of atoms (conduction) or through space (radiation). In aliquid or gas, currents will facilitate the transfer of heat (convection).
1. Because air is not a good thermal conductor2. Metal is a good thermal conductor, so the heat of the stove is transferred to the food.
Quick Review◆ Conduction is the transfer of thermal energy with
no overall transfer of matter.
◆ Conduction occurs within a material or betweenmaterials that are touching.
◆ Conduction in gases is slower than in liquids and solids because the particles in a gas collide less often.
Questions1. Explain why the air space in a double-pane
window provides thermal insulation.
2. Explain why pots and pans are often metal.
A Model of Energy Transfer in Conduction
Methods of Heat TransferS8P2.d Describe how heat can be transferred through matter by thecollisions of atoms (conduction) or through space (radiation). In aliquid or gas, currents will facilitate the transfer of heat (convection).
Quick Review◆ A lever is a rigid bar that is free to rotate around a
fixed point (the fulcrum).
◆ First-class levers always change the direction of theinput force. Second-class levers increase force, butdo not change its direction. Third-class leversincrease distance, but do not change the directionof the input force.
◆ To calculate the ideal mechanical advantage of anylever, divide the input distance by the outputdistance.
Questions1. Which class of lever always has a mechanical
advantage of less than 1?
2. Which class of lever always has a mechanicaladvantage that is greater than 1?
A B CFirst-Class Lever Second-Class Lever Third-Class Lever
Simple MachinesS8P3.c Demonstrate the effect of simple machines (lever, inclinedplane, pulley, wedge, screw, and wheel and axle) on work.
Quick Review◆ A wheel and axle is a simple machine that consists
of two disks or cylinders fastened together thatrotate around a common axis. The object with thelarger axis is called the wheel and the object withthe smaller axis is called the axle.
◆ To calculate the ideal mechanical advantage of awheel and axle, divide the radius of the wheel bythe radius of the axle.
Questions1. Does a steering wheel have a mechanical
advantage of greater or less than 1?
2. Other than the examples shown, give an example of a wheel and axle you use regularly.
Simple MachinesS8P3.c Demonstrate the effect of simple machines (lever, inclinedplane, pulley, wedge, screw, and wheel and axle) on work.
Quick Review◆ Waves are disturbances that transfer energy from
place to place.
◆ Transverse waves move the particles in a mediumat right angles to the direction in which the wavestravel. Longitudinal waves move the particlesparallel to the direction in which the waves travel.
◆ Waves that require a medium through which totravel are called mechanical waves.
Questions1. How could two people holding each end of a
slightly stretched metal coil create a transversewave? A longitudinal wave?
2. What controls the amplitude of a transverse wavecreated by two people holding each end of aslightly stretched metal coil?
1. Start the wave with a back-and-forth arm motion across the line of the coil; start the wave with a push-pull armmotion in line with the coil.
2. The distance the arm motion displaces the coil across the direction of the coil
WavesS8P4.a Identify the characteristics of electromagnetic and mechanicalwaves.
Quick Review◆ When a wave hits a surface through which it
cannot pass, it bounces off, or is reflected.
◆ The angle of incidence is equal to the angle ofreflection for all waves and reflecting surfaces.
◆ When a wave moves from one medium into anothermedium at an angle, it changes speed, which causesit to bend, or be refracted.
Questions1. What is the angle of incidence?
2. If the angle of incidence of a wave is 30°, what isthe angle of reflection?
3. Suppose a wave hits a surface that is partiallyimpenetrable at an angle. On the other side of thesurface is a more dense medium. What will happento the wave?
1. The angle between an incoming wave and an imaginary line perpendicular to the surface2. 30°3. Part of the wave would reflect at the surface, and part would enter the denser medium, where it would be bent, or refracted.
ReflectionS8P4.b Describe how the behavior of light waves is manipulatedcausing reflection, refraction, diffraction, and absorption.
Quick Review◆ The eye focuses and detects light. It sends signals
from detected light to the brain.
◆ The cornea, iris, pupil, and lens of the eye all helpform an image on the retina.
◆ Rod cells work best in dim light and enable you tosee black, white, and shades of gray. Cone cells workbest in bright light and enable you to see colors.
Questions1. Which cells in the retina are more active outdoors
during the day?
2. In dim light, which part of the eye becomes larger toallow in more light?
A. cornea B. iris
C. pupil D. lens
1. Cone cells 2. C
Cornea
Opticnerve
Iris
Lens
Bloodvessels
Retina
Pupil
Fluid-filled chamber
LightS8P4.c Explain how the human eye sees objects and colors in terms ofwavelengths.
Quick Review◆ The primary colors of light are red, green, and blue.
When combined in equal amounts, they producewhite light.
◆ The primary colors of pigments are cyan, yellow,and magenta. When combined in equal amounts,they produce black pigment.
◆ Secondary colors are combinations of two primarycolors of light or of pigment.
Questions1. What are the three secondary colors of light?
2. What are the three secondary colors of pigments?
3. Compare the primary colors of pigments with thesecondary colors of light. What do you notice? Whyis this true?
1. Cyan, yellow, and magenta2. Red, green, and blue
Primary colors of light Primary colors of pigments
LightS8P4.c Explain how the human eye sees objects and colors in terms ofwavelengths.
3. Primary colors of pigment are the same as secondary colors of light, and vice versa. Pigment colors are due to absorption of light, so they result from absence of light rather than emission of light.
Quick Review◆ Mechanical waves, such as sound and seismic
waves, are produced when a source of energy causes a medium to vibrate. Sound waves travelthrough the air; seismic waves travel through theearth’s layers.
◆ Electromagnetic waves, such as light, transfer electric and magnetic energy and do not need amedium to travel through.
Questions1. What do sound waves and seismic waves have in
common?
2. How are sound waves and light waves different?
1. They both spread away from the source. 2. Light waves travel without a medium.
82
Waves in a MediumS8P4.d Describe how the behavior of waves is affected by medium(such as air, water, solids).
Quick Review◆ Light waves travel faster in air than in water. They
travel slower in glass than in water.
◆ When light enters a medium where its speedchanges, it bends. This is called refraction.
◆ The index of refraction of a material is a measureof how much light bends when it enters thatmaterial. The amount light bends varies withwavelength.
Questions1. Why does a stick appear bent when placed in a
transparent container filled with water?
2. Why do rainbows appear if the angle of the sun isjust right after a rainstorm?
3. What object uses refraction to separate white lightinto all the colors of the visible spectrum?
Light
1. Because light travels slower in water, the image of the stick is refracted.2. Tiny water droplets refract the range of wavelengths in sunlight by slightly differing amounts, separating the light into colors. 3. A glass prism
use 7
Waves in a Medium: RefractionS8P4.d Describe how the behavior of waves is affected by medium(such as air, water, solids).
Quick Review◆ The Doppler effect is the apparent change in the
pitch of a sound as the source or observer move relative to one another.
◆ Radar devices use the Doppler effect to determinethe speed of moving objects such as cars.
◆ The Doppler effect is also used to study weatherand the expansion of the universe.
Questions
1. Why does each observer in the diagram hear asound with a different pitch?
2. How can the Doppler effect be used to measure thespeed of a thunderstorm?
Observer A(decreasedfrequency)
Observer B(increasedfrequency)
1. The waves have a lower frequency at Observer A than at Observer B.2. Waves are sent toward the storm. They bounce off particles of precipitation. The frequency of the returning waves
changes as the storm moves.
SoundS8P4.e Relate the properties of sound to everyday experiences.
Quick Review◆ Wavelength is the distance between two
corresponding parts of a wave.
◆ Frequency is the number of complete waves thatpass a certain point in a certain amount of time. It is measured in hertz (Hz), or number of waves per second.
◆ The pitch of a sound that you hear depends on thefrequency of the sound wave.
◆ Amplitude is the maximum distance the particles ofa medium carrying a wave move from their restpositions.
Questions1. How can wavelength be expressed in terms of wave
speed and frequency?
2. As a wave’s energy increases, what happens to itsamplitude?
1. Wavelength = Speed ÷ Frequency 2. It increases.
WavesS8P4.f Diagram the parts of the wave and explain how the parts areaffected by changes in amplitude and pitch.
Quick Review◆ Gravity is an attractive force between any two
objects that have mass.
◆ The strength of a gravitational force depends onmass and distance. The force is stronger for largermasses and at shorter distances.
◆ The gravitational attraction between Earth and anobject gives an object weight.
◆ The sun’s gravitational pull holds Earth and otherplanets in their orbits.
Questions1. Why does it seem that objects such as cars and
rocks do not have gravitational attraction towardeach other?
2. Why is the weight of an object on the moon lessthan the weight of the same object on Earth?
3. What causes ocean tides?
1. The mass of these objects is very small compared to Earth,so the force attracting them to Earth is much stronger than the force attracting them to each other.
2. The mass of the moon is less than the mass of Earth,so the gravitational force is smaller.
3. The moon’s gravity pulling on the Earth.
The force of gravity acts between all objects.
If mass increases, the force of gravity increases.
If distance increases, the force of gravity decreases.
GravityS8P5.a Recognize that every object exerts gravitational force on everyother object and that the force exerted depends on how much massthe objects have and how far apart they are.
Quick Review◆ Inertia and gravity combine to keep Earth in orbit
around the sun and the moon in orbit around Earth.
Questions1. Why does the moon stay in orbit around Earth?
Why doesn’t the moon fall to Earth?
2. What would happen to the moon if there were no gravity?
A. It would stop moving.
B. It would fall toward Earth.
C. It would leave orbit and move in a straight line.
D. It would continue to orbit Earth.
1. Inertia keeps the moon moving ahead, and gravity pulls the moon toward Earth. The combination of these two factors keeps the moon in orbit around Earth.
2. C
Force ofgravity
Moon’s motionwithout gravity
Actual orbit Moon
Earth
GravityS8P5.a Recognize that every object exerts gravitational force on everyother object and that the force exerted depends on how much massthe objects have and how far apart they are.
Quick Review◆ On Earth, gravity is a downward force that pulls
objects towards Earth’s center.
◆ In free fall, the force of gravity is an unbalancedforce, which causes an object to accelerate.
Questions1. In the absence of air resistance, which object in the
diagram would hit the ground first?
A. the leaf
B. the acorn
C. Both would hit the ground at the same time.
D. It’s impossible to say without more information.
2. How can you describe the net force acting on theacorn in the diagram?
1. C2. Subtract the force of air resistance from the force of gravity. The result is a downward net force pulling
the acorn towards Earth’s center.
Gravity
Gravity
Airresistance
Airresistance
GravityS8P5.a Recognize that every object exerts gravitational force on everyother object and that the force exerted depends on how much massthe objects have and how far apart they are.
Quick Review◆ An electric circuit is a path through which electric
charges flow.
◆ All circuits consist of a source of electrical energy(such as a battery), a conducting wire, and a devicethat uses the electrical energy, such as a light bulb.A switch is often included in a circuit to turn adevice on or off.
◆ Electric circuits can transform electrical energy intoelectromagnetic, thermal, or mechanical energy.
Questions1. A light bulb transforms electrical energy into what
kind of energy?
2. What components must all circuits have in order towork?
3. What change must be made to the ciruit shown inthe diagram above in order for current to flow?
1. Electromagnetic, or light, energy and thermal energy 2. A battery, a wire, and a device that uses electrical energy3. The switch must be closed for current to flow.
Circuit Symbols
Circuit Diagram
Switch
Wire
Energy source
Resistor
+ –
+ –
Electric CircuitsS8P5.b Demonstrate the advantages and disadvantages of series andparallel circuits and how they transfer energy.
Quick Review◆ Current flows when the terminals of a voltage
source are connected to complete a circuit.
◆ A series circuit has only one path through which current can flow. Parallel circuits have multiplepaths.
◆ In a circuit diagram, each circle with a jagged linerepresents a resistance, such as a light bulb.
Questions1. Suppose a series circuit has a battery and three
glowing light bulbs. How many of the bulbs wouldcontinue to glow after one burned out? Why?
2. Suppose a parallel circuit has a battery and threeglowing light bulbs. How many of the bulbs wouldcontinue to glow after one burned out? Why?
3. Is the circuit formed by all the lights and appliances in a home a series or parallel circuit?
1. None; there is only one path for the current to take, and the burned-out bulb has broken the circuit.2. Two; the current can still flow through the other two paths in the circuit.3. Parallel
Series Circuit Parallel Circuit
Electric CircuitsS8P5.b Demonstrate the advantages and disadvantages of series andparallel circuits and how they transfer energy.