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Science Standards Review: Energy. S8P2. Students will be familiar with the forms and transformations of energy. . a. Explain energy transformation in terms of the Law of Conservation of Energy. . The law of conservation of energy states that: . Energy is never destroyed

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S8P2. Students will be familiar with the forms and transformations of energy.

a. Explain energy transformation in terms of the Law of Conservation of Energy.


The law of conservation of energy states that
The law of conservation of energy states that: transformations of energy.

  • Energy is never destroyed

  • Energy is never created

  • Energy may be transformed or converted from one form to another

  • Energy is constantly changing forms


b. 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.

  • 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: light, electricity, mechanical motion, sound) and their characteristics.

Heat(thermal)—the vibration and movement of the atoms and molecules within substances

ex. Atoms move faster in hot water vs. ice water

Light (radiant)—is electromagnetic energy

ex. Sunlight, X-rays,

microwaves, p.636

Electricity—energy of moving electrons, typically moving through a wire

ex. lightening


Sound light, electricity, mechanical motion, sound) and their characteristics. —energy caused by an object’s vibrations

Mechanical Motion—is energy stored in a moving object or an object that can move

PE + KE = mechanical energy

ex. Wind, Jack in the Box


Chemical light, electricity, mechanical motion, sound) and their characteristics. —energy 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

Nuclear—energy stored in the nucleus of an atom — the energy that

holds the nucleus together

ex. Nuclear power plants

http://www.eia.doe.gov/kids/energy.cfm?page=about_forms_of_energy-basics

http://www.bbc.co.uk/schools/ks2bitesize/science/physical_processes/


d. 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 the collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (convection). 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 collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (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 collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (convection).

  • 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!

Examples

Energy from the sun

Microwaves use radiation


Review Questions the collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (convection).

Which of the following converts electrical

energy into mechanical?

A light switch B electric stove

C light bulb D electric fan


According 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 joules B. 150 joules

  • C. 100 joules D. 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 energy

    • B. kinetic energy

    • C. force due to gravity

    • D. friction


    A house becomes warm after air circulates in the house. What type of heat transfer happens?

    Conduction

    Convection

    Radiation



    Where is kinetic energy the greatest? What type of heat transfer happens?

    A B C D

    Where is potential energy the greatest?

    A B C D


    Tonya 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) A

    B) 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?

    Conduction

    Convection

    Radiation


    At which position in the pendulum swing is kinetic energy greatest?

    a. A b. B

    c. C d. D

    At which position in the pendulum swing is potential energy the lowest?

    a. A b. B

    c. C d. D


    What type of heat transfer is happening in the picture? greatest?

    A. Heat to electrical

    B. Chemical to mechanical

    C. Mechanical to light

    D. Heat to mechanical

    What type of heat transfer is happening in the air around the candle?

    Conduction

    Convection

    Radiation


    A gasoline-powered vehicle goes up a hill from point X to point Y. What energy transformation must occur in the car’s engine?

    A Chemical energy into mechanical energy

    B Electrical energy into light energy

    C Electrical energy into sound energy

    D Mechanical energy into light energy


    When 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. Conduction B. convection

    • C. Expansion D. radiation

    Heat, light, and electricity are all forms of

    • A. Atoms B. energy

    • C. Cells D. motion


    The batteries in a flashlight make electricity using often feels heat coming off the pavement. The heat is moving from the asphalt to the person by

    • 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?

    Conduction

    Convection

    Radiation


    S8P3. Students will investigate relationship between force, mass, and the motion of objects.

    a. Determine the relationship between velocity and acceleration.


    • Velocity mass, and the motion of objects. —

      • the speed of an object in a particular direction

      • velocity must include speed (distance over time) anddirection!

      • ex. an airplane travels west at 600 km/h

      • if speed or direction changes the velocity changes


    Practice: mass, and the motion of objects.

    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?

    Tom

    Sally


    • Acceleration mass, and the motion of objects. —

      • 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


    b. Demonstrate the effect of balanced and unbalanced forces on an object in terms of gravity, inertia, and friction.


    • Balanced Forces on an object in terms of gravity, inertia, and friction.

      • 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, bird’s nest


    • Unbalanced Forces on an object in terms of gravity, inertia, and friction.

      • 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



    • Gravity— or unbalanced force

      • A force of attraction between objects due

      • to their masses

      • Law of Universal Gravity—all objects in the

      • universe attract each other through

      • gravitational force

    +

    Yes, you really are attracted to your science book!


    a. 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.


    • The more mass, the more

    • gravitational force


    • Inertia— every other object and that the force exerted depends on how much mass the objects have and how far apart they are.

      • The tendency of objects to resist any

      • changes in motion

      • The more mass the more inertia

    More mass more inertia

    Less mass less inertia


    • Friction— every other object and that the force exerted depends on how much mass the objects have and how far apart they are.

      • 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


    c. Demonstrate the effect of simple machines (lever, inclined plane, pulley, wedge, screw, and wheel and axle) on work.


    • Inclined Plane inclined plane, pulley, wedge, screw, and wheel and axle) on work. —

      • A flat slanted surface

      • Less input force necessary, but must be exerted over a longer distance

      • Examples: ramps, stairs,


    • Wedge inclined plane, pulley, wedge, screw, and wheel and axle) on work. —

      • 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


    • Screw inclined plane, pulley, wedge, screw, and wheel and axle) on work. —

      • An inclined plane wrapped around a cylinder

      • The 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


    • Wheel and Axle inclined plane, pulley, wedge, screw, and wheel and axle) on work. —

      • Two circular objects fastened together that rotate about a common axis

      • The 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 distance

    • Examples: door knobs, steering wheels, screw drivers

    wheel

    axle


    • Levers inclined plane, pulley, wedge, screw, and wheel and axle) on work. —

      • A rigid bar that pivots or rotates about a fixed point called a fulcrum

    3 different classes (types) of levers

    • 1) 1st Class Levers—

      • Fulcrum (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

    Effort

    Load

    Effort

    Fulcrum

    Fulcrum

    Output/load


    • 2 inclined plane, pulley, wedge, screw, and wheel and axle) on work. nd 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 distance

    • Examples: Bottle openers, wheelbarrows

    Input force (effort)

    fulcrum

    load


    • 3 inclined plane, pulley, wedge, screw, and wheel and axle) on work. rd Class Levers—

    • The input force (effort) is between the

    • fulcrum and the load

    • Do not change the direction of the input force

    • Does not multiply your input force (effort) but allows you to apply a lot of force over a shorter distance

    • Examples: Tweezers, Rake, baseball bat, Hammer


    Remember inclined plane, pulley, wedge, screw, and wheel and axle) on work. FLE

    1st Class– fulcrum in the middle

    2nd Class– load is in the middle

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

    load

    Input force (effort)

    fulcrum

    Output/load

    effort

    fulcrum


    • Pulley inclined plane, pulley, wedge, screw, and wheel and axle) on work. —

      • Grooved wheel with a rope

      • (or chain, or cable) wrapped around it

      • Can change the amount and direction of your input force

    • Fixed Pulleys—

      • A pulley attached to a structure

      • Does not change the amount of input force

      • Changes the direction of the input force

    Example: flag pole, sail boat, elevators


    • Moveable Pulley— inclined plane, pulley, wedge, screw, and wheel and axle) on work.

      • A pulley attached to the object being moved

      • Does not change the direction of the force

      • Does increase your force—you use less force over more distance

    • Example: a crane


    • Pulley System (Block and Tackle)— inclined plane, pulley, wedge, screw, and wheel and axle) on work.

    • Combination of fixed and moveable pulleys

    • Changes the size and direction of the force you exert


    Review Questions inclined plane, pulley, wedge, screw, and wheel and axle) on work.

    Which characteristic of motion could change without changing the velocity of an object?

    A the speed B the position

    C the direction D the acceleration


    Which 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? 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 50 N. B 150 N.

    C 200 N. D 350 N.


    This box will increase in speed 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 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 plane B. pulley

    • C. Wedge D. lever

    Which simple machine is a pair of scissors?

    • A. wheel and axle

    • B. pulley

    • C. inclined plane

    • D. lever


    On Earth, an astronaut has a mass of 140 kg. When the astronaut goes into space, she

    • will 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 A

    • B. Arrow B

    • C. Arrow C

    • D. Arrow D


    Which term refers to the rate of change of motion? indicated by Arrow A. Which arrow shows the direction in which the boat would move?

    • A. Acceleration B. speed

    • C. Momentum D. velocity

    The tendency for a body at rest to remain at rest is known as

    • A. inertia

    • B. torque

    • C. momentum

    • D. mass



    Which force causes a moving object to slow and then stop? minimize the amount of force needed to lift the box?

    • A. Acceleration B. inertia

    • C. Friction D. lift


    S8P4. Students will explore the wave nature of sound and electromagnetic radiation.

    a. Identify the characteristics of electromagnetic and mechanical waves.


    • Mechanical Waves— electromagnetic radiation.

    • Waves that need a medium—a substance through which the wave can travel

    • Can be transverse or longitudinal

    • Ex. sound waves, ocean waves

    • Electromagnetic Waves—

    • Waves that do not need a medium—a substance through which the wave can travel

    • All are transverse waves

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


    b. Describe how the behavior of light waves is manipulated causing reflection, refraction diffraction, and absorption.


    • Reflection— causing reflection, refraction diffraction, and absorption.

    • occurs when waves bounce off an object

    • We see objects as different colors when that color is reflected back at us

    • Ex.—A leaf appears green because it reflects green light


    • Absorption– causing reflection, refraction diffraction, and absorption.

    • The transfer of energy carried by light to particles of matter

    • The farther light travels from its source the more it is absorbed by particles (this is why light becomes dimmer)


    • Refraction— causing reflection, refraction diffraction, and absorption.

    • The bending of a wave as it passes from one medium to another

    • Light travels slower through matter causing light to bend


    • Diffraction— causing reflection, refraction diffraction, and absorption.

    • 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



    ROYGBIV



    • Sound through media— (such as air, water, solids).

      • Sound travels quickly though air

      • Even faster through liquids

      • Fastest through solids

    Warmer objects will conduct sound faster

    Why?

    Particles move faster in warm object so they transfer the sound faster

    http://www.teachersdomain.org/asset/phy03_vid_zlistenstick/

    http://egfl.net/Teaching/Resources/Animations/homepage.html



    • Sound— (such as air, water, solids).

      • a longitudinal wave caused by vibrations and carried through a substance

      • has to travel through a medium


    • Doppler Effect— (such as air, water, solids).

      • 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


    • Echo— (such as air, water, solids).

    • Reflected sound wave

    • Occur when sound bounces off a flat hard surface


    f. Diagram the parts of the wave and explain how the parts are affected by changes in amplitude and pitch.


    Parts of the wave— are affected by changes in amplitude and pitch.

    Crest—the highest point of a transverse wave

    Trough—the lowest point of a transverse wave

    Wavelength—the distance from any point on one wave to an identical point on the next wave

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


    wavelength are affected by changes in amplitude and pitch.

    Crest

    Amplitude

    Rest Position

    Trough


    Remember: are affected by changes in amplitude and pitch.

    AL PF

    Amplitude/loudness Pitch/Frequency

    • The 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 quiet are affected by changes in amplitude and pitch.

    This wave will sound loud


    Frequency—the 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 of timea high pitch.

    This wave would have a low pitch.


    • Review Questions of time

    • Which color reflects all colors of light?

    • A. black B. white

    • C. green D. 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. Diffraction B. reflection

    • C. Interference D. refraction


    There 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 Joseph’s 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. White B. yellow

    • C. Black D. 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 rail

    • A. is heated by friction

    • B. carries sound better than air

    • C. is cooler than air

    • D. is connected directly to the train


    Sound A has a shorter wavelength than Sound B. This means that Sound A will

    • A. 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 that Sound A will

    • A. Air B. metal

    • C. Water D. outer space


    A. B. C. D. that Sound A will

    Which wave has the highest frequency?

    Which wave has the highest pitch?

    Which wave has the softest sound?

    Which wave has the loudest sound?


    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 electricity, and magnetism as major kinds of forces acting in nature.

    • Series Circuits—

      • All parts of the circuit are connected in a single loop

      • Only one path for charges to follow

      • All loads share the same current


    • Disadvantages electricity, and magnetism as major kinds of forces acting in nature.

    • Only one pathway for moving charges

    • If there is a break in the circuit charges stop flowing

    • (ex. if one light blows all the lights go out)

    • Advantages

    • Burglar alarms use series circuits


    • Parallel Circuits— electricity, and magnetism as major kinds of forces acting in nature.

    • Loads are connected side by side

    • Charges have more than one path on which they can travel

    • Loads do not have the same current (each light will shine at full brightness)

    • houses are wired in parallel


    c. Investigate and explain that electric currents and magnets can exert force on each other.


    • Electric Current— magnets can exert force on each other.

    • The rate at which charges pass a given point

    • Expressed in amperes (amps)


    • How an object becomes charged… magnets can exert force on each other.

      • If it loses electrons it becomes positively charged

      • If it gains electrons it becomes negatively charged

    • Charged objects create electric force

      • Greater the charge, the greater the force

      • Closer the charges, the greater the force


    • Magnets- magnets can exert force on each other.

      • Anything that attracts iron or things made of iron

      • Have two poles (strongest attraction here)

      • Exert force on each other (magnetic force)

      • Surrounded by magnetic field


    • Electromagnetism— magnets can exert force on each other.

    • Interaction between electricity and magnetism

    • Electric currents produce a magnetic field


    Review Questions magnets can exert force on each other.

    At which location is Earth’s magnetic field the strongest?

    1 B. 2

    C. 3 D. 4


    In which circuit will the bulb light up? magnets can exert force on each other.

    A.

    B.

    C.

    D.


    Which best describes a parallel circuit? magnets can exert force on each other.

    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 because battery, as shown, and all are lit. If bulb I is unscrewed and removed, what will happen to the other two light bulbs?

    • A. the switch is too far away from the bulb

    • B. the bulb has to be larger

    • C. the wires are not long enough

    • D. there is no energy source


    Which electromagnet will pick up the most paper clips? battery, as shown, and all are lit. If bulb I is unscrewed and removed, what will happen to the other two light bulbs?

    A.

    B.

    C.

    D.


    Which diagram is a parallel circuit? battery, as shown, and all are lit. If bulb I is unscrewed and removed, what will happen to the other two light bulbs?


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