# Energy and Heat Select a topic: Potential and kinetic energy

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Energy and Heat Select a topic: Potential and kinetic energy
Heat and temperature Heat transfer Heat insulators and conductors

I should study some more
The word “potential” means something is able to do something, but it is not doing it right now 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!!! Name: Rusty 4 + 2 = 8 6 – 3 = 12 5 x 2 = 11 7 x 0 = 7 = 8 8 – 6 = -3 1 + 1 = 2 5 x 4 = 20 83 x 7 = 98 = 6.6 Name: Rusty 4 + 2 = 6 6 – 3 = 3 5 x 2 = 10 7 x 0 = 0 = 67 8 – 6 = 2 1 + 1 = 2 5 x 4 = 20 83 x 7 = 581 = 11.1 Rusty I should study some more

Potential energy is stored energy
Potential energy is stored energy. Potential energy has no motion; its energy is not being used. Person on diving board Stretched rubber band Hanging weight The rubber band has potential energy The person has potential energy 50 tons The weight has potential energy

The word “kinetic” means moving
The words “kinetic” and “cinema” both come from the same Greek word for moving. Movie cinemas show moving pictures. click here to play movie …they would look like this: If you looked at the 5 pictures in this film strip just one at a time…

Person falling into water
Kinetic energy is moving energy (remember: kinetic is just another word for moving) Person falling into water Flying rubber band Falling weight 50 tons 50 tons

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.

See what you’ve learned about potential & kinetic energy
That’s the end of this section. Click here to go home Q: What does “potential” mean? Q: True or false: kinetic energy is stored energy? A: Potential means able to do something (but not doing it) A: False Q: What is potential energy? Q: What type of energy does a skier resting on a mountain top have? A: Stored energy (or unused energy) A: Potential energy Q: What does “kinetic” mean? A: Kinetic means moving Q: Which of these is an example of potential energy being converted into kinetic energy? a car stopping at a stop sign a ball rolling down the stairs an igloo resting on an iceberg 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: a ball rolling down the stairs A: potential energy

Remember that everything is made of atoms: Water is just 2 hydrogen atoms stuck with 1 oxygen atom (H2O) Water molecules magnified 50,000,000 times H O Glass of water H O H O H O H O H O H O H O

All atoms and molecules vibrate – they have energy and are always shaking
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. H O H O H O H O H O I finally stopped moving 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!

3 molecules of water with different amounts of kinetic energy:
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 3 molecules of water with different amounts of kinetic energy: Low kinetic energy Medium kinetic energy High kinetic energy H O H O H O (low vibration) (medium vibration) (high vibration)

Heat/temperature is just a measurement of how much kinetic (vibrating) energy something has
90 80 70 60 50 40 30 20 10 90 80 70 60 50 40 30 20 10 Low energy High energy H O H O

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…

Let’s write some imaginary numbers for each water molecule to measure how much energy they have
2 5 10

Heat is the total kinetic energy
Bottle B Bottle A 9 5 9 3 10 + 5 2 4 + 3 2 16 32 10 5 10 4 Bottle B has 32 heat units Bottle A has 16 heat units

Bottle A has more heat than Bottle B
5 5 2 4 + 10 2 16 5 4 Bottle B has 10 heat units Bottle A has 16 heat units

Temperature is the average kinetic energy
Bottle B Bottle A 5 2 4 + 9 9 8 10 + 5 8 2 16 27 10 5 4 16 ÷ 4 molecules = 4 27 ÷ 3 molecules = 9 Bottle A has 4 temperature units Bottle B has 9 temperature units

Bottle B has a higher temperature than Bottle A
5 5 2 4 + 2 10 16 5 4 Bottle A has 4 temperature units (16 ÷ 4 molecules = 4) Bottle B has 10 temperature units (10 ÷ 1 molecule = 10)

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)? OUCH! Boiling water (212° F) 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. Pretty hot! Oven (450° F)

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. Zoom in of match Zoom in of iceberg match iceberg

See what you’ve learned about heat and temperature
That’s the end of this section. Click here to go home Q: What is everything made out of? 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: Atoms (or molecules) Q: True or False: heat and temperature are the same thing. A: The house that’s 70° F A: False Q: When an atom cools off, what happens to its vibration? Q: Are all atoms still or vibrating? A: They are always vibrating. The more they vibrate, the more heat & temperature they have A: It vibrates more slowly Q: If 1 molecule in something vibrates more quickly, what will increase? 1) only heat 2) only temperature 3) heat and temperature 4) nothing Q: What measures the average kinetic energy of something? A: Temperature A: heat and temperature Q: What measures the total kinetic energy of something? A: Heat

Heat moves from hot objects to cold objects
Let’s add some hot coffee to the cup… 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. Cup temperature Coffee temperature 90 80 70 60 50 40 30 20 10 90 80 70 60 50 40 30 20 10 heat heat heat heat heat heat

Because ice is colder than your finger, the heat from your finger moves into the ice. Heat moves from hot things to cold things 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. finger 90 80 70 60 50 40 30 20 10 90 80 70 60 50 40 30 20 10 heat ice

Can you draw some arrows that show where heat will flow in this room?
Home Sweet Home 72° (air) 30° 212° 150° 42° 200° 130° 375° 72° 90° 72° 72°

Can you draw some arrows that show where heat will flow in this room?
Heat will move from any warmer object toward any cooler object Home Sweet Home 72° (air) 30° 212° 150° 42° 200° 130° 375° 72° 90° 72° 72°

An energy source is something that gives away energy; an energy receiver is something that takes energy Football Source (quarterback) Football Receiver Energy source Energy receiver Energy receiver finger Energy source ice heat heat

See what you’ve learned about heat transfer
Q: Use the word bank below to fill in the blanks in the red sentence: thin cool light fast slow thick warm heavy “Heat moves from _______ objects to _______ objects.” 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 ______.” That’s the end of this section. Click here to go home warm cool heat ice book 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 ______.” 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? Tomato 80°F Ice 20°F A: Heat will move from the tomato into the ice until they both have the same temperature. 30° ° heat heat book ice Energy source Energy receiver

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 I N S U L A T O R heat heat heat heat

Brrrr – it’s freezing outside!
Clothes do not give you heat; clothes keep you warm because they trap your body’s heat. heat heat My wool hat is a great insulator. Insulators don’t let heat go through them. My body’s heat now stays with me. heat heat Brrrr – it’s freezing outside! heat heat

List of conductors and insulators
Diamond 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 Great conductors/ bad insulators Bad conductors/ great insulators

See what you’ve learned about conductors & insulators
That’s the end of this section. Click here to go home Q: What is the difference between a heat conductor and a heat insulator? Circle all the objects below that are heat insulators: plastic metal cotton wood wool 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: If a metal desk leg and a wooden desk leg both have a temperature of 75˚ F, why does the metal leg feel colder? Q: What is wrong with Alexi’s statement: “I will put on my socks because my socks give me extra heat”? 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. 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: Hey, guess what? A: That’s what.

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