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Potential and kinetic energy
Heat and temperature
Heat transfer
Heat insulators and conductors
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The word “potential” means something is able to do something, but it is not doing it right now
Name: Rusty
1. 4 + 2 = 62. 6 – 3 = 33. 5 x 2 = 104. 7 x 0 = 05. 23 + 44 = 676. 8 – 6 = 27. 1 + 1 = 28. 5 x 4 = 209. 83 x 7 = 58110. 6.1 + 5 = 11.1
Rusty, this quiz is below your potential. I believe you can
do better! Please try again….
Rusty, you have used your potential – great work – I
knew you could do it!!!
Rusty
I should study some more
Name: Rusty
1. 4 + 2 = 82. 6 – 3 = 123. 5 x 2 = 114. 7 x 0 = 75. 23 + 44 = 86. 8 – 6 = -37. 1 + 1 = 28. 5 x 4 = 209. 83 x 7 = 9810. 6.1 + 5 = 6.6
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Potential energy is stored energy.Potential energy has no motion; its energy is not being used.
Person on diving board
Stretched rubber band
50 tons
Hanging weight
The person has potential
energy
The weight has potential energy
The rubber band has potential energy
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The word “kinetic” means movingThe words “kinetic” and “cinema” both come from the same Greek
word for moving. Movie cinemas show moving pictures.
If you looked at the 5 pictures in this film strip just one at a time…
…they would look like this:
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50 tons
Kinetic energy is moving energy(remember: kinetic is just another word for moving)
Person falling into
water
Flying rubber band
50 tons
Falling weight
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Potential energy can change into kinetic energy
The skier at the top of the mountain
has a lot of potential energy.
As the skier goes down the mountain, her
potential energy turns into kinetic energy.
Once the skier has stopped, she has no more potential or kinetic energy.
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See what you’ve learned about potential & kinetic energy
Q: What does “potential” mean?A: Potential means able to do something (but not doing it)
Q: What is potential energy?A: Stored energy (or unused energy)
Q: What does “kinetic” mean?A: Kinetic means moving
Q: What is kinetic energy?A: Moving energy
Q: What type of energy does a bow & arrow have if the bow is pulled back?A: potential energy
Q: True or false: kinetic energy is stored energy?A: False
Q: What type of energy does a skier resting on a mountain top have?A: Potential energy
Q: Which of these is an example of potential energy being converted into kinetic energy?
1) a car stopping at a stop sign2) a ball rolling down the stairs3) an igloo resting on an icebergA: a ball rolling down the stairs
That’s the endof this section.
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Home
Remember that everything is made of atoms: Water is just 2 hydrogen atoms stuck with 1
oxygen atom (H2O)
magnified 50,000,000
timesH
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H OH
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Water molecules
Glass of water
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All atoms and molecules vibrate –they have energy and are always shaking
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Some molecules of water: Remember that a “molecule” is just a bunch of atoms stuck together. Water is just 2 atoms of hydrogen connected to 1 atom of oxygen.
Well actually, you are still moving. Although you look still, all the atoms in your body are always vibrating. Your atoms and their vibrations are
just too tiny for our eyes to see.
Help! I can’t stop moving!
I finally stopped moving
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Molecules with more energy vibrate faster:to say a molecule vibrates a lot is the same as saying the molecule has a lot of kinetic energy
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Low kinetic energy
Medium kinetic energy
High kinetic energy
3 molecules of water with different amounts of kinetic energy:
(low vibration) (medium vibration) (high vibration)
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Heat/temperature is just a measurement of how much kinetic (vibrating) energy
something has
HH
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O
Low energy
High energy
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HEAT and TEMPERATURE are not the same thing
• Heat is the total kinetic energy something has (another word for heat is thermal energy)
• Temperature is the average kinetic energy something has
We’ll now see exactly what this difference means…
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Let’s write some imaginary numbers for each water molecule to measure how much energy they have
1052
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Heat is the total kinetic energy
Bottle A
5 4
5
2
5254+
16
Bottle A has 16 heat units
Bottle B
10 10
9
3
93
1010+32
Bottle B has 32 heat units
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Bottle A has more heat than Bottle B
Bottle A
5 4
5
2
5254+
16
Bottle A has 16 heat units
Bottle B
10
Bottle B has 10 heat units
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Temperature is the average kinetic energy
Bottle A
5 4
5
2
5254+
16
Bottle A has 4 temperature units
Bottle B
10
9
8
98
10+27
Bottle B has 9 temperature units
16 ÷ 4 molecules = 4 27 ÷ 3 molecules = 9
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Bottle B has a higher temperature than Bottle A
Bottle A
5 4
5
2
5254+
16
Bottle A has 4 temperature units (16 ÷ 4 molecules = 4)
Bottle B
10
Bottle B has 10 temperature units (10 ÷ 1 molecule = 10)
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Question: Why might you quickly stick your hand into a hot oven (450° F) but you would never quickly stick your hand into a pot of boiling water (212° F)?
Oven (450° F)
Boiling water (212° F)
Pretty hot!
OUCH!
Answer: Boiling water has a lot more heat than the oven’s air (even though the air has a higher temperature). The oven’s air is less dense than the pot’s water.
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An iceberg has a lower temperature than a burning match, but much more heat!
A match has a greater temperature than the iceberg because the average molecule in the
match is moving faster than the average molecule in the iceberg. The iceberg has
more heat than the match because it is SO MUCH LARGER, so all of its slow moving molecules have more total kinetic energy
than the match’s molecules.
iceberg
Zoom in of icebergZoom in of match
match
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See what you’ve learned about heat and temperature
Q: What is everything made out of? A: Atoms (or molecules)
Q: True or False: heat and temperature are the same thing.A: False
Q: Are all atoms still or vibrating?A: They are always vibrating. The more they vibrate, the more heat & temperature they have
Q: What measures the average kinetic energy of something?A: Temperature
Q: What measures the total kinetic energy of something?A: Heat
Q: Which of these has the most heat?1) house (70° F) 2) match (500° F)3) house (50° F) 4) match (100° F)
A: The house that’s 70° F
Q: When an atom cools off, what happens to its vibration?A: It vibrates more slowly
Q: If 1 molecule in something vibrates more quickly, what will increase?1) only heat 2) only temperature3) heat and temperature 4) nothingA: heat and temperature
That’s the endof this section.
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Heat moves from hot objects to cold objects
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The heat from the coffee goes into the cup because the cup is colder than the coffee.
The coffee cools off and the cup warms up until they have the same temperature.
heat
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Cup temperature
Coffee temperature
Let’s add some hot coffee to the cup…
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Because ice is colder than your finger, the heat from your finger moves into the ice. Heat moves from hot
things to cold things
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Ice does not make your finger colder by adding coldness to your finger. Ice makes your finger colder by stealing heat away from your finger, leaving your finger colder.
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Can you draw some arrows that show where heat will flow in this room?
212°30°
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200° 130° 72°
Home Sweet Home
Home
Home Sweet Home
Can you draw some arrows that show where heat will flow in this room?
212°30°
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Heat will move from any warmer object toward
any cooler object
HomeEnergy source
An energy source is something that gives away energy; an energy receiver is something that takes energy
Football Source(quarterback)
Football Receiver
icefinger heat
Energy source Energy
receiver
Energy receiver
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See what you’ve learned about heat transferQ: Use the word bank below to fill in the blanks in the red sentence:thin cool light fastslow thick warm heavy“Heat moves from _______ objects to _______ objects.”
warmcool
Q: Use the word bank below to fill in the blanks in the red sentence:ice book coldness heat“If an ice cube (temperature 20° F) is placed on top of a book (temperature 70° F), then ______ will flow from the ______ into the ______.”
heaticebook
Q: Use the word bank below to fill in the blanks in the red sentence:ice book coldness heat“If an ice cube (temperature 20° F) is placed on top of a book (temperature 10° F), then ______ will flow from the ______ into the ______.”
heatice book
Tomato80°F
Ice20°F
Q: Below is a tomato next to an ice cube. Where will heat move, when will heat stop moving, what is the energy receiver, what is the energy source?
A: Heat will move from the tomato into the ice until they both have the same temperature.heat
30° 30°
That’s the endof this section.
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Energy source
Energy receiver
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I N S U L A T O R
Heat moves through some materials more easily than others
• Conductors are materials that let heat pass through them easily
• Insulators are materials that don’t let heat pass through them easily
C O N D U C T O R
heat
heat
heatheat
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Clothes do not give you heat; clothes keep you warm because they trap your body’s heat.
heat
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My wool hat is a great insulator. Insulators don’t
let heat go through them. My body’s heat now stays with me.
Brrrr – it’s freezing outside!
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List of conductors and insulatorsDiamond 500,000.0
Copper 40,000.0
Gold 30,000.0
Aluminum 21,600.0
Concrete 100.0
Glass 80.0
Water 58.0
Wood 13.0
Polystyrene 12.5
Glass wool insulation 3.8
Styrofoam 2.7
Air 2.4
Argon 1.6
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See what you’ve learned about conductors & insulators
Q: What is the difference between a heat conductor and a heat insulator?A: A conductor is something that lets heat move through it easily; an insulator is something that does not let heat move through it easily.
Q: What is wrong with Alexi’s statement: “I will put on my socks because my socks give me extra heat”?A: Unless the socks are warmer than Alexi, they don’t give him any heat. However, socks are good insulators; they trap the heat in Alexi’s feet and don’t let it escape.
Q: If a metal desk leg and a wooden desk leg both have a temperature of 75˚ F, why does the metal leg feel colder?A: Metal is a good conductor, so it easily steals the heat away from your hand, causing your hand to get/feel cold. Wood is a good insulator: it does not steal much heat away from your hand.
Q: Hey, guess what?A: That’s what.
Circle all the objects below that are heat insulators:
plastic metal cotton wood wool
That’s the endof this section.
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