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Science Standards Review:Energya. Explain energy transformation in terms of the Law of Conservation of Energy. S8P2. Students will be familiar with the forms and transformations of energy. The law of conservation of energy states that: Energy is never destroyedEnergy is never createdEnergy may be transformed or converted from one form to anotherEnergy is constantly changing formsb. Explain the relationship between potential and kinetic energy. Kinetic Energy

Energy of Motion Depends on Speed Mass More speed = more KE More mass = more KE

Potential Energy Energy of position (stored energy) Gravitational PE depends on Weight Height More weight = more PE More height = more PE

c. Compare and contrast the different forms of energy (heat, light, electricity, mechanical motion, sound) and their characteristics. Forms of Energy:

Heat (thermal)the vibration and movement of the atoms and molecules within substances ex. Atoms move faster in hot water vs. ice waterLight (radiant)is electromagnetic energy ex. Sunlight, X-rays, microwaves, p.636

Electricityenergy of moving electrons, typically moving through a wire ex. lightening

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Soundenergy caused by an objects vibrationsMechanical Motionis energy stored in a moving object or an object that can movePE + KE = mechanical energy ex. Wind, Jack in the Box

9Chemicalenergy stored in the bonds of atoms and molecules (is released during chemical changes when atoms are rearranged)ex. Cells in our body store chemical energy

Nuclearenergy stored in the nucleus of an atom the energy that holds the nucleus together ex. Nuclear power plantshttp://www.eia.doe.gov/kids/energy.cfm?page=about_forms_of_energy-basicshttp://www.bbc.co.uk/schools/ks2bitesize/science/physical_processes/

10d. Describe how heat can be transferred through matter by the collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (convection). Conduction is the transfer of energy through matter from particle to particle as they touch. Transfer of heat energy from atom to atom

Most effective in solids.

Heat moves from warmer substances to cooler substances.

Convection

the transfer of thermal energy by the movement of a gas or liquid (a medium).

The circular motion caused by density differences that result from temperature differences are called convection currents.

Radiation the transfer of thermal energy by electromagnetic waves such as visible light and infrared waves. (See p. 636-637).

This energy can be transferred through particles of matter OR empty space!ExamplesEnergy from the sunMicrowaves use radiation

Review QuestionsWhich of the following converts electrical energy into mechanical? A light switchB electric stoveC light bulbD electric fanAccording to the Law of Conservation of Energy, if Sally throws a watermelon with 100 joules of energy off the roof of a building, how much energy should the watermelon have as it hits the ground?

200 joulesB. 150 joulesC. 100 joulesD. 0 Joules When a rock is thrown straight up into the air, it reaches its highest point and briefly comes to a complete stop before it starts to fall back to the ground. Which is greatest at the point where the rock stops? A. potential energyB. kinetic energyC. force due to gravityD. frictionA house becomes warm after air circulates in the house. What type of heat transfer happens?ConductionConvectionRadiation

Why do we insulate our soda cans?To keep heat in To keep heat outTo keep cold in To keep cold out

Where is kinetic energy the greatest?ABCD

Where is potential energy the greatest?ABCDTonya drops a ball off a cliff as shown in the picture. Which position shows where the ball has the most kinetic energy and the least potential energy? A) AB) B C) C

Bob sat by the pool too long and his skin began to burn. What type of heat transfer occurred to make him burn?ConductionConvectionRadiation

At which position in the pendulum swing is kinetic energy greatest?a. Ab. Bc. Cd. DAt which position in the pendulum swing is potential energy the lowest?a. Ab. Bc. Cd. D

What type of heat transfer is happening in the picture?A. Heat to electricalB. Chemical to mechanicalC. Mechanical to lightD. Heat to mechanicalWhat type of heat transfer is happening in the air around the candle?ConductionConvectionRadiation

A gasoline-powered vehicle goes up a hill from point X to point Y. What energy transformation must occur in the cars engine? A Chemical energy into mechanical energy B Electrical energy into light energy C Electrical energy into sound energy D Mechanical energy into light energyWhen walking along an asphalt street after sundown, a person often feels heat coming off the pavement. The heat is moving from the asphalt to the person by A. ConductionB. convectionC. ExpansionD. radiationHeat, light, and electricity are all forms ofA. AtomsB. energyC. CellsD. motion

The batteries in a flashlight make electricity using A. chemical B. solar C. heat D. mechanical In the pictures below, the candle is heating the water in the tank. Which picture shows how the water will move as it gets hot?

My dog, Ralph, wears slippers on hot days because the pavement is hot on his feet. What type of heat transfer makes his feet hot?ConductionConvectionRadiationa. Determine the relationship between velocity and acceleration. S8P3. Students will investigate relationship between force, mass, and the motion of objects. Velocity the speed of an object in a particular direction velocity must include speed (distance over time) and direction! ex. an airplane travels west at 600 km/h if speed or direction changes the velocity changes

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Practice:Tom is traveling west at 50 miles per hour. Sally and her family are traveling south at 50 miles per hour. Do the cars have the same velocity? Why or why not?

TomSally31Acceleration The rate at which velocity changes An object accelerates if its speed or direction changes an increase in velocity is called positive acceleration a decrease in velocity is called negative acceleration or deceleration the faster the velocity changes, the greater the acceleration

32b. Demonstrate the effect of balanced and unbalanced forces on an object in terms of gravity, inertia, and friction. Balanced Forces Occur when the forces on an object produce a net force of 0 Newtons (N) Will not cause a change in the motion of a moving object Will not cause a nonmoving object to start moving ex. Hat on your head, birds nest

34Unbalanced Forces Occur when the net force on an object is not 0 Newtons (N) The forces are unbalanced Produce a change in motion Are necessary to start movement or change movement ex. kicking a ball

35Decide whether the following pictures represent a balanced or unbalanced force

36Gravity A force of attraction between objects due to their masses Law of Universal Gravityall objects in the universe attract each other through gravitational force

+Yes, you really are attracted to your science book!37a. Recognize that every object exerts gravitational force on every other object and that the force exerted depends on how much mass the objects have and how far apart they are. Gravity decreases as distance increases. The more mass, the more gravitational force

39Inertia The tendency of objects to resist any changes in motion The more mass the more inertia

More mass more inertiaLess mass less inertia40Friction A force that opposes motion between two surfaces that are in contact Can cause a moving object to slow down and eventually stop Caused by roughness of surfaces

41c. Demonstrate the effect of simple machines (lever, inclined plane, pulley, wedge, screw, and wheel and axle) on work. Inclined Plane A flat slanted surface Less input force necessary, but must be exerted over a longer distance

Examples: ramps, stairs,

43Wedge Device that is thick at one end and tapers to a thin edge at the other end (two inclined planes back to back) The longer and thinner the wedge, the less input force is required (same as with the inclined plane)Examples: End of an ax, knife, zipper,Push pin

44ScrewAn inclined plane wrapped around a cylinderThe closer the threads, the greater the mechanical advantage (longer distance, but less input force needed)

Examples: Jar lid, bolts, faucets

The closer the threads the greater the mechanical advantage 45Wheel and Axle Two circular objects fastened together that rotate about a common axisThe object with the larger diameter is the wheel and the object with the smaller diameter is the axle Multiplies your force, but you must exert your force over a longer distanceExamples: door knobs, steering wheels, screw drivers

wheelaxle

46LeversA rigid bar that pivots or rotates about a fixed point called a fulcrum

3 different classes (types) of levers1) 1st Class LeversFulcrum (pivot point) is located between the input and output force (the load).Change the direction of the force (they can also change size or distance of the force)

Examples: Seesaw, scissors, pliers, catapult

EffortFulcrumLoad

EffortFulcrumOutput/load472nd Class Levers The load is between the fulcrum and input force (effort) Do not change the direction of the input force You must exert less force over more distanceExamples: Bottle openers, wheelbarrows

fulcrumInput force (effort)load

483rd Class LeversThe input force (effort) is between the fulcrum and the loadDo not change the direction of the input forceDoes not multiply your input force (effort) but allows you to apply a lot of force over a shorter distanceExamples: Tweezers, Rake, baseball bat, Hammer

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loadfulcrumInput force (effort)Remember FLE

1st Class fulcrum in the middle

2nd Class load is in the middle

3rd Class Effort (input force) is in the middle

fulcrumeffortOutput/load50

Example: flag pole, sail boat, elevators

PulleyGrooved wheel with a rope (or chain, or cable) wrapped around itCan change the amount and direction of your input force

Fixed PulleysA pulley attached to a structureDoes not change the amount of input forceChanges the direction of the input force

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Moveable PulleyA pulley attached to the object being movedDoes not change the direction of the forceDoes increase your forceyou use less force over more distance Example: a crane

52Pulley System (Block and Tackle)Combination of fixed and moveable pulleysChanges the size and direction of the force you exert

53Which characteristic of motion could change without changing the velocity of an object? A the speedB the positionC the directionD the acceleration Review QuestionsWhat two forces are responsible for keeping Earth in orbit around the sun?Gravity and frictionGravity and inertia c. Friction and inertia d. Strong force and inertiaWhich of the following represents the velocity of a moving object?

A spring scale is pulled downward and readings are recorded. If the spring is pulled 3.5 cm, the spring scale should read A 12 N. B 13 N. C 14 N. D 15 N.

A ball is dropped from the top of a tall building. As the ball falls, the upward force of air resistance becomes equal to the downward pull of gravity. When these two forces become equal in magnitude, the ball will A flatten due to the forces.B fall at a constant speed.C continue to speed up.D slow to a stop.

What is the net force on the cart above?A 50 N. B 150 N. C 200 N. D 350 N.

This box will increase in speed A downward and to the left.B downward and to the right.C upward and to the left.D upward and to the right.When you bend your arm at the elbow, the bones and muscles in your arm are acting as a system. What simple machine does this system represent? A. inclined planeB. pulleyC.WedgeD. lever

Which simple machine is a pair of scissors? A. wheel and axleB. pulleyC. inclined planeD. leverOn Earth, an astronaut has a mass of 140 kg. When the astronaut goes into space, shewill have a mass of 140 kg, but will have less weight. will have less mass and weight. will have a mass of 140 kg, and have a weight of 140 kg. will have less mass and a weight of 140 kg.

A person dives out of a nonmoving boat in the direction indicated by Arrow A. Which arrow shows the direction in which the boat would move? A. Arrow AB. Arrow BC. Arrow CD. Arrow DWhich term refers to the rate of change of motion? A. AccelerationB. speedC. MomentumD. velocityThe tendency for a body at rest to remain at rest is known asA. inertiaB. torqueC. momentumD. massWhere should Melissa position the fulcrum in order to minimize the amount of force needed to lift the box? Point A B. Point B C. Point C D. Point D

Which force causes a moving object to slow and then stop? A. AccelerationB. inertiaC. FrictionD. liftS8P4. Students will explore the wave nature of sound and electromagnetic radiation. a. Identify the characteristics of electromagnetic and mechanical waves. Mechanical WavesWaves that need a mediuma substance through which the wave can travel Can be transverse or longitudinal

Ex. sound waves, ocean wavesElectromagnetic WavesWaves that do not need a mediuma substance through which the wave can travelAll are transverse waves

Ex. light, microwaves, TV &Radio waves, X-rays

67b. Describe how the behavior of light waves is manipulated causing reflection, refraction diffraction, and absorption. Reflection occurs when waves bounce off an object We see objects as different colors when that color is reflected back at usEx.A leaf appears green because it reflects green light

69Absorption The transfer of energy carried by light to particles of matterThe farther light travels from its source the more it is absorbed by particles (this is why light becomes dimmer)

70Refraction The bending of a wave as it passes from one medium to another Light travels slower through matter causing light to bend

71Diffraction The bending of waves around barriers or through openings Amount of diffraction depends on wavelength and size of barrier or opening Wavelength of light is small so it cannot bend very much

72c. Explain how the human eye sees objects and colors in terms of wavelengths.

We see different wavelengths of visible light as different colors Longest wavelengths are red Shortest wavelengths are violet

ROYGBIV74d. Describe how the behavior of waves is affected by medium (such as air, water, solids). Sound through mediaSound travels quickly though airEven faster through liquidsFastest through solidshttp://egfl.net/Teaching/Resources/Animations/homepage.htmlhttp://www.teachersdomain.org/asset/phy03_vid_zlistenstick/Warmer objects will conduct sound fasterWhy? Particles move faster in warm object so they transfer the sound faster76e. Relate the properties of sound to everyday experiences. Sound a longitudinal wave caused by vibrations and carried through a substance has to travel through a medium

78Doppler Effect Apparent change in the frequency of a sound caused by the motion of the listener or the source of the sound The sound will have a higher pitch as it approaches Will have a lower pitch as it leaves

79EchoReflected sound waveOccur when sound bounces off a flat hard surface

80f. Diagram the parts of the wave and explain how the parts are affected by changes in amplitude and pitch. Parts of the waveCrestthe highest point of a transverse waveTroughthe lowest point of a transverse waveWavelengththe distance from any point on one wave to an identical point on the next wave

Amplitudethe maximum distance that the particles of a wave vibrate from their rest position

wavelengthTroughCrestRest PositionAmplitudeRemember:AL PFAmplitude/loudnessPitch/FrequencyThe amplitude of a wave is related to height.

The greater the amplitude the louder the sound and the more energy it has.

This wave will sound loudThis wave will sound quiet

Frequencythe number of waves produced in a given amount of time

The frequency of a wave determines pitch.

A wave with a high frequency has a high pitch.

A wave with a low frequency has a low pitch.

This wave would have a high pitch.This wave would have a low pitch.Review Questions

Which color reflects all colors of light? A.blackB. whiteC. greenD. red

When Marcia yelled from the top of a canyon, an echo was created. This happened because the sound waves of her voice bounced back from the canyon walls. Which property of waves occurred? A. DiffractionB. reflectionC. InterferenceD. refractionThere is only one fish in the fishbowl below. When Joseph looks down at the fish, the image he observes is closer to the surface than the actual location of the fish.

Which wave characteristic does Josephs observation demonstrate? A. amplitude B. diffraction C. reflection D. refraction Why are light-colored clothes cooler to wear in the summer than dark-colored clothes? A. Light-colored clothes let more air in.B. Light-colored clothes prevent sweating.C. Light colored clothes are not as heavy as dark-colored clothes.D. Light-colored clothes reflect more light than dark-colored clothes.A family is building an outdoor shower at their cottage by hanging a plastic container from a post, as shown above. The container will be exposed to full sunlight. What color should the container be to make the water as warm as possible? A. WhiteB. yellowC. BlackD. red

In old movies, people sometimes put their ear on a railroad track to see if a train is coming. This works because the iron railA. is heated by frictionB. carries sound better than airC. is cooler than airD. is connected directly to the train

Sound A has a shorter wavelength than Sound B. This means that Sound A willA. be louder than Sound B.B. be softer than Sound B.C. have a lower pitch than Sound B.D. have a higher pitch than Sound B.Sound can travel fastest through A. AirB. metalC. WaterD. outer spaceWhich wave has the highest frequency?

Which wave has the highest pitch?

Which wave has the softest sound?

Which wave has the loudest sound?

A.B. C. D.S8P5. Students will recognize characteristics of gravity, electricity, and magnetism as major kinds of forces acting in nature. b. Demonstrate the advantages and disadvantages of series and parallel circuits and how they transfer energy. Types of Circuits: Series and Parallel

Series CircuitsAll parts of the circuit are connected in a single loopOnly one path for charges to followAll loads share the same current

97DisadvantagesOnly one pathway for moving chargesIf there is a break in the circuit charges stop flowing(ex. if one light blows all the lights go out)

AdvantagesBurglar alarms use series circuits

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Parallel CircuitsLoads are connected side by sideCharges have more than one path on which they can travelLoads do not have the same current (each light will shine at full brightness) houses are wired in parallel

99c. Investigate and explain that electric currents and magnets can exert force on each other. Electric CurrentThe rate at which charges pass a given pointExpressed in amperes (amps)

101How an object becomes chargedIf it loses electrons it becomes positively chargedIf it gains electrons it becomes negatively charged

Charged objects create electric forceGreater the charge, the greater the forceCloser the charges, the greater the force102Magnets-Anything that attracts iron or things made of ironHave two poles (strongest attraction here)Exert force on each other (magnetic force)Surrounded by magnetic field

103ElectromagnetismInteraction between electricity and magnetism Electric currents produce a magnetic field

104At which location is Earths magnetic field the strongest?1B. 2C. 3D. 4

Review QuestionsIn which circuit will the bulb light up?

A.B.C.D.Which best describes a parallel circuit? A Electricity flows along one pathway. B The flow of electricity comes from one source.C Electricity flows along more than one pathway. D The flow of electricity comes from more than one source

Three identical light bulbs are connected in parallel with a battery, as shown, and all are lit. If bulb I is unscrewed and removed, what will happen to the other two light bulbs?

A. Both will stay lit.B. II will go out, but III will stay lit.C. II will stay lit, but III will go out.D. Both will go out.

The bulb in the electric circuit will NOT light becauseA. the switch is too far away from the bulbB. the bulb has to be largerC. the wires are not long enoughD. there is no energy source

Which electromagnet will pick up the most paper clips? A.B.C.D. Which diagram is a parallel circuit?A. B. C. D.