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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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slide2

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:
  • Energy is never destroyed
  • Energy is never created
  • Energy may be transformed or converted from one form to another
  • Energy is constantly changing forms
slide4

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
slide5

Potential Energy

  • Energy of position (stored energy)
  • Gravitational PE depends on
    • Weight
    • Height
  • More weight = more PE
  • More height = more PE
slide7

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

slide8

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 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

slide9

Sound—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

slide10

Chemical—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/

slide11

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).

slide12

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.
slide13

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.

slide14

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!

Examples

Energy from the sun

Microwaves use radiation

slide15

Review Questions

Which of the following converts electrical

energy into mechanical?

A light switch B electric stove

C light bulb D electric fan

slide16

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
slide17

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
slide18

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

Conduction

Convection

Radiation

slide19

Why do we insulate our soda cans?

    • To keep heat in
    • To keep heat out
    • To keep cold in
    • To keep cold out
slide20

Where is kinetic energy the greatest?

A B C D

Where is potential energy the greatest?

A B C D

slide21

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

slide22

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

slide23

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

slide24

What type of heat transfer is happening in the picture?

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

slide25

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

slide26

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
slide27

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?

slide28

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

slide29

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

a. Determine the relationship between velocity and acceleration.

slide30

Velocity—

    • 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
slide31

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?

Tom

Sally

slide32

Acceleration—

    • 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
slide33

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

slide34

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, bird’s nest
slide35

Unbalanced 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
slide37

Gravity—

    • 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!

slide38

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.

slide39

Gravity decreases as distance increases.

  • The more mass, the more
  • gravitational force
slide40

Inertia—

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

More mass more inertia

Less mass less inertia

slide41

Friction—

    • 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
slide42

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

slide43

Inclined Plane—

    • A flat slanted surface
    • Less input force necessary, but must be exerted over a longer distance
    • Examples: ramps, stairs,
slide44

Wedge—

    • 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
slide45

Screw—

    • 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

slide46

Wheel and Axle—

    • 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

slide47

Levers—

    • 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

slide48

2nd 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

slide49

3rd 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
slide50

Remember 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

slide51

Pulley—

    • 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

slide52

Moveable Pulley—

    • 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
slide53

Pulley System (Block and Tackle)—

  • Combination of fixed and moveable pulleys
  • Changes the size and direction of the force you exert
slide54

Review Questions

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

slide55

What two forces are responsible for keeping Earth in orbit around the sun?

    • Gravity and friction
    • Gravity and inertia
  • c. Friction and inertia
  • d. Strong force and inertia

Which of the following represents the velocity of a moving object?

slide56

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.

slide57

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.

slide58

What is the net force on the cart above?

A 50 N. B 150 N.

C 200 N. D 350 N.

slide59

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.

slide60

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
slide61

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.
slide62

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
slide63

Which term refers to the rate of change of motion?

  • 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
slide64

Where 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
slide65

Which force causes a moving object to slow and then stop?

  • A. Acceleration B. inertia
  • C. Friction D. lift
slide66

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

a. Identify the characteristics of electromagnetic and mechanical waves.

slide67

Mechanical Waves—

  • 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
slide68

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

slide69

Reflection—

  • 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
slide70

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)
slide71

Refraction—

  • The bending of a wave as it passes from one medium to another
  • Light travels slower through matter causing light to bend
slide72

Diffraction—

  • 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
slide74

We see different wavelengths of visible light as different colors

  • Longest wavelengths are red
  • Shortest wavelengths are violet

ROYGBIV

slide76

Sound through media—

    • 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

slide78

Sound—

    • a longitudinal wave caused by vibrations and carried through a substance
    • has to travel through a medium
slide79

Doppler 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
slide80

Echo—

  • Reflected sound wave
  • Occur when sound bounces off a flat hard surface
slide81

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

slide82

Parts of the wave—

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

slide83

wavelength

Crest

Amplitude

Rest Position

Trough

slide84

Remember:

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.
slide85

This wave will sound quiet

This wave will sound loud

slide86

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.

slide87

This wave would have a high pitch.

This wave would have a low pitch.

slide88

Review Questions

  • 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
slide89

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

slide90

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.
slide91

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
slide92

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
slide93

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.
slide94

Sound can travel fastest through

  • A. Air B. metal
  • C. Water D. outer space
slide95

A. B. C. D.

Which wave has the highest frequency?

Which wave has the highest pitch?

Which wave has the softest sound?

Which wave has the loudest sound?

slide96

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.

slide97

Types of Circuits: Series and Parallel

  • 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
slide98

Disadvantages

  • 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
slide99

Parallel Circuits—

  • 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
slide100

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

slide101

Electric Current—

  • The rate at which charges pass a given point
  • Expressed in amperes (amps)
slide102

How an object becomes charged…

    • 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
slide103

Magnets-

    • 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
slide104

Electromagnetism—

  • Interaction between electricity and magnetism
  • Electric currents produce a magnetic field
slide105

Review Questions

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

1 B. 2

C. 3 D. 4

slide107

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

slide108

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.
slide109

The bulb in the electric circuit will NOT light because

  • 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
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