Energy
Energy-Mind Map
Electrical Energy
Potential Energy
Solar Energy
Kinetic Energy
Heat & Light
Thermal Energy
Nuclear Energy
Acoustic Energy
Wind/Mechanical
Energy
Vocabulary
Energy- the ability to do work
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Anything that has energy can do work
Measured in Joules [J]
Work-work is done when a force is responsible for the motion of an object
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Ex: a person pushing a lawn mower (person applies force on mower- makes mower
move=work)
Ex: How much work does a force directed up do on a box that is not moving?
no work is done because the box is not moving- there is no force causing a change in
motion
Measured in Joules [J]
Power- the rate at which work is done; the speed at which energy is used
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Symbol= P
Measured in Watts [W]
Potential Energy- energy that is stored for use at a later time
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Symbol= PE
Measured in Joules [J]
Kinetic Energy- the energy of motion
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Symbol= KE
Measured in Joules [J]
Substance- a form of matter
Compound- a combination of elements
Ex: CO2 gas in a bottle, liquid H2O in a cup
Molecule- the smallest part of a compound
Ex: 1 CO2,
1 H2O
Element- a natural and pure substance
Ex: hydrogen gas, a bar of solid gold
Atom- the smallest part of an element
Ex: 1 H, 1 Au
Proton- a positively charged particle in the atom
Neutron- a neutral (not charged) particle in the atom
Electron- a negatively charged particle in the atom
The Structure of the Atom
Nucleus- the dense center of an atom
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The atom is 99.9% empty space (a BB in a Pennsylvania sized balloon)
The nucleus contains over 99.9% of the atoms mass
Electrons (-)
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Electrons have the smallest mass of any particle ( 9.11 x 10-31)
Electrons orbit the nucleus in cloud like patterns (not in nucleus)
Electrons electrically balance the charge of the atom
Electrons allow atoms to bond with other atoms to form molecules
Protons (+)
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Protons have 10,000 more mass than electrons
Protons are located inside the nucleus of the atom
The number of protons in an atom defines what the identity of the element
o Ex: H=1p, He=2p, O=16p
Neutrons (0)
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Neutrons have about the same mass as a proton
Neutrons are located inside the nucleus
Neutrons stabilize the atom and prevent it from exploding
Basic Energy
Work- is done when there is a force that is responsible for the motion of an object
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It requires energy to do work
W=F x d
Work= Force x distance
Measured in Joules [J]
o Ex: how much work must be done to push a box with 10N a distance of 20m?
W=F x d W= 10 x 20
W=200J
o Ex: How much work does a force directed up do on a box that is not moving?
no work is done because the box is not moving- there is no force causing a change in
motion
Potential Energy- Energy that is stored for use at a later time
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There are three basic types of potential energy: gravitational, chemical, and elastic
o Gravitational PE- energy that is stored by lifting objects to higher heights
 Ex: lift a stapler from the floor and hold it in your hands
 PE=magh (Potential Energy= mass x gravity x height)
 Measured in Joules [J]
o
Chemical Energy- energy that is stored in molecules, like food, gasoline and wood
o
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Elastic Energy- energy that is stored in items that can be stretched, like rubber bands,
hair ties, springs
Ex: A box of 4 kg mass is placed 5m above the ground. Find the PE.
PE=magh
PE=4(10)5 PE=200J
Kinetic Energy- energy of motion
 Anything that is moving has KE
 It takes work to make something move or stop moving
 KE=½ mv2
Kinetic Energy= ½ mass x velocity2
o
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Measured in Joules [J]
Ex: A 4 kg toy car is moving at 4 m/s. Find the KE.
KE=½ mv2
KE= ½ (4)(42)
KE= ½ (4) (16) KE=2(16)
KE=32 J
Power-the rate at which work is done
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Working faster is more power; working slower is less power
𝑊
P=
(Power= Work / change in time)
∆𝑡
Measured in [J/s]=[W] watt
o Ex: A motor does 24,000 J of work every 60 seconds. Find Power.
𝑊
24,000
P=
P=
P=4oo Watts
∆𝑡
60
TYPES OF ENERGY
Mechanical Energy- (Kinetic Energy)
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The form of energy where one moving object causes a second object to move
o Examples: pushing down on a lever, using a pulley, turning a screwdriver, using a key in
a lock, throwing a baseball
Acoustic Energy- (Kinetic Energy)
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The form of energy that moves in sound waves
Work is done to vibrate air, vibrating air travels in a chain reaction, the vibrating air beats on the
ear drum of the listener
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Sound cannot travel in space
o Nobody can hear you scream in space because there is no air to vibrate
Electrical Energy (Potential Energy & Kinetic Energy)
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The form of energy dealing with the flow or storage of electrons
o It is easier to move an electron than a proton because it takes less force to move the
smaller mass of an electron
A battery (PE) is a device that stores electrons close together
o When a battery is used, the electrons flow from the negative side to the
positive side of the battery
o A battery is dead when the electrons are balanced out (charge is balanced)
Electricity is the flow of moving electrons and is a form of kinetic energy
o Voltage is a measure of how unbalanced the charge is
o There are two conditions for a battery to work
 Must be a complete circuit
 Must be an unbalanced charge or voltage on the battery
Nuclear Energy (Potential Energy)
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Fission- the release of nuclear energy by breaking the atoms apart
o Only works with heavy elements like: Uranium
o Used most in the world by humans
Fusion- the release of nuclear energy by combining atoms together
o Only works with light elements like: Hydrogen
o Used in the sun
Radiant Energy (Kinetic Energy)- the form of energy dealing with the movement of light
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Light moves at a speed of 300 million m/s
Light is a combination of electricity and magnetism
Light has the ability to move energy even in empty space
o Light moves through space from the sun to earth and brings heat with it
Plants are special because they can use light to make food (photosynthesis)
Thermal Energy (Kinetic Energy)- The form of energy dealing with the motion of atoms
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Temperature- is the measure of the average kinetic energy of the moving atoms in a substance
o Requires only one object
Heat- the amount of energy that moves from one object to another object
o Heat requires two objects
o Heat always flows from high temperature to low temperature
Heat stops flowing when the temperatures are equal
Thermal Energy is measured with temperature and moves in the form of heat
o If something is hot, thermal energy is moving into you
o If something is cold, thermal energy is leaving you
 Methods of Heat Transfer
o
Conduction- the transfer of heat through direct contact
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Ex: accidently touching the stove top, bare feet on a hot pavement
Convection-the transfer of heat through the movement of a liquid or gas
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Ex: boiling water, a warm/cool wind, taking a shower
Radiation- the transfer of heat that is carried by electromagnetic waves (EM waves)
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Ex: getting a sunburn, light, microwaves,
Conservation of Energy Law
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Energy cannot be created or destroyed
Energy can change into different forms or transfer into different objects
o PE changes to PE when an object falls from a height
Whenever energy changes forms, it loses some quality (releases some heat)
o The less changes energy goes through, the more efficient a system is
o
Etoti=Etotf
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(total energy before an event=total energy after an event)
EX: A car has 200 J of Chemical energy. It turns 50 J into Kinetic Energy. How
much heat was created?
Etoti=Etotf
CE=KE + q
200=50+q
150 J=q
Energy III: Energy Waves
Vocabulary
Wave- an efficient way to move energy (doesn’t lose much of the energy as it moves it)
Wave Length-the distance a wave travels in one complete wave cycle
Frequency- the number of times a wave repeats itself in one second
Symbol- f
1
f=𝑇 frequency=1/period
1
Pitch- the property of sound (frequency) that makes it high or low sounding
Period- the length of time it takes a wave to complete one wave cycle
Symbol- T
Amplitude-the strongest part of the wave (loudness for sound)
Crest- the highest point on the wave
Trough-the lowest point in the wave
Decibel- the unit for sound (measures how loud the sound is); [db]
Fault- cracks in the earth separating two land masses
Focus- the exact point where the earth moves causing an earthquake; epicenter
T=𝑓 period=1/frequency
Medium- the material that energy uses travels
Ex: water is the medium that ocean waves travel through; air is the medium for sound
waves
Magnitude- how strong something is
Oscilloscope- a device used to measure sound waves
Seismograph- a device used to measure the strength of an earthquake
Rarefaction- the stretched out portion of a wave
Compression-the bunched together portion of a wave
Waves
Waves- vibrations that carry energy from place to place
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Waves are like delivery trucks that carry energy
Waves move like falling dominos (the energy travels from start to finish but each domino only
moves a little bit)
Energy moves from place to place but the particles only move a little bit
Two Basic Types of Waves
Transverse Wave- waves that vibrate perpendicular to the motion of the wave
Longitudinal Waves- waves that vibrate parallel to the motion of the wave
Compression
Sound
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Sound waves carry acoustic energy
Sound waves move through vibrations in a material (medium)
If no medium is available (space), then sound cannot exist
How to Measure Sound
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There are two ways to measure sound: pitch and loudness
You can measure the pitch with an oscilloscope that measures frequency
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You can measure the loudness of sound with the decibel scale
o Decibel- the unit for the loudness of sound [db]
Rarefaction
Decibel Scale- for each increase of 10 Decibels, the sound gets 10 times louder
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0 [db]-the threshold of hearing (smallest possible sound we can hear)
1 [db]- a leaf blowing across the ground
20 [db]- a purring cat
30 [db]- two people talking
40 [db]- standard TV volume
50 [db]-classroom noise in a lab
60 [db] a big dog barking
65 [db]- the classroom during a lab experiment
70 [db] a building fire alarm
80 [db]- factory with big machines running
100 [db]- jackhammer breaking concrete
120 [db] sold out rock concert
130 [db]- the threshold of pain (the sound that really starts to hurt the ears); near an
airplane on takeoff
140 [db]-a firecracker blowing up; being in the first few rows of a concert; firing a gun next
to someone’s ear
Compared to 1 dB
10 dB
20 dB
30 dB
40 dB
50 dB
Loudness
10x
100x
1000x
10,000x
100,000x
How many times louder is 40 dB than 20 dB?
-added 20 dB, so 40 decibels is 100x’s louder than 20 dB
How many times louder is 50 dB than 10 dB?
-added 40 dB, so 50 dB is 10,000x’s louder than 10 dB
How many times louder is 50 dB louder than 30 dB?
-added 20 dB, so 50 dB is 100x’s louder than 30 dB
SHORT CUT: Count how many tens it goes up by, then add that many zeros to the number 1
Seismic Waves
Seismic Waves- waves that carry the ability to do lots of work (earthquake waves)
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Seismic waves can be heard and felt, but not seen
Earthquakes form when tectonic plates collide or slide against one another
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Seismic waves spread out from the focus or epicenter
3 Types of Seismic Waves
P-Waves- Seismic waves that move through the liquid rock portion of the earth
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The deepest waves- located in the core of the earth
You will never experience them
S-Waves- Seismic waves that move through the solid parts of the earth (mantle and crust)
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Not likely to experience these unless you are in a cave underground
Ground Waves- seismic waves that move on the surface of the earth
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Source of earthquakes and cause the most damage (most devastating)
Seismographs- used to measure the strength of an earthquake
Big
Earthquake
Normal
Small
Earthquake
o
They can detect vibrations in the ground a few thousand miles away
Richter Scale- the method for labeling how strong an earthquake is
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The Rule: each increase of 1 is 10 times stronger
Richter Scale
o
o
1
2
3
4
Strength of Earthquake Compared
to 1
E (energy)
10E
100E
1,000E
5
10,000E
6
100,000E
7
1,000,000E
8
10,000,000E
9
100,000,000E
10
1,000,000,000E
How many times stronger is a 5 than a 3 earthquake?
added 2, so 100x’s stronger
How much stronger is a 2 than a 8 earthquake?
added 6, so 1000,000x’s stronger
Where earthquakes are first noticeable by
humans
Earthquakes that are a little scary (minor
damage)
First level where earthquakes cause damage
(structural damage)
Devastating (buildings falling over; bridges
collapse; sinkholes)
Total destruction
SHORT CUT: Count how many times it increases by, then add that many zeros to the number 1 to get
the strength
Electromagnetic Waves (E/M)
Electromagnetic waves- carry radiant and thermal energy (sunglight)
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Do NOT need any material to travel in
They can travel in space!
E/M Spectrum- the set of seven electromagnetic waves that carry energy through radiation
Radio- Microwave-Infrared-Visible LIGHT (ROYGBIV)-Ultraviolet-X-Ray- Gamma Ray
Longest wavelength
Shortest wavelength
Smallest Energy
Highest Energy
Low Frequency
High Frequency
ALL have the
SAME SPEED
V=3.0 x 108 [m/s]
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Ultraviolet, x-rays and gamma rays are harmful to humans
Visible, infrared, microwave and radio waves are low risk to humans