Presentation on theme: "Home Potential and kinetic energy Heat and temperature Heat transfer Heat insulators and conductors Select a topic:"— Presentation transcript:
Home Potential and kinetic energy Heat and temperature Heat transfer Heat insulators and conductors Select a topic:
Home The word potential means something is able to do something, but it is not doing it right now Name: Rusty = – 3 = x 2 = x 0 = = – 6 = = x 4 = x 7 = = 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 = – 3 = x 2 = x 0 = = – 6 = = x 4 = x 7 = = 6.6
Home 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
Home The word kinetic means moving The 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:
Home 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
Home 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.
Home See what youve 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 sign 2)a ball rolling down the stairs 3)an igloo resting on an iceberg A: a ball rolling down the stairs Thats the end of this section. Click here to go home
Home Remember that everything is made of atoms: Water is just 2 hydrogen atoms stuck with 1 oxygen atom (H 2 O) magnified 50,000,000 times HH O HH O HH O HH O HH O HH O HH O HH O Water molecules Glass of water
Home All atoms and molecules vibrate – they have energy and are always shaking HH O HH O HH O HH O HH O 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 cant stop moving! I finally stopped moving
Home 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 HH O HH O HH O 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)
Home Heat/temperature is just a measurement of how much kinetic (vibrating) energy something has HH O HH O Low energy High energy
Home 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 Well now see exactly what this difference means…
Home Lets write some imaginary numbers for each water molecule to measure how much energy they have
Home Heat is the total kinetic energy Bottle A Bottle A has 16 heat units Bottle B Bottle B has 32 heat units
Home Bottle A has more heat than Bottle B Bottle A Bottle A has 16 heat units Bottle B 10 Bottle B has 10 heat units
Home Temperature is the average kinetic energy Bottle A Bottle A has 4 temperature units Bottle B Bottle B has 9 temperature units 16 ÷ 4 molecules = 427 ÷ 3 molecules = 9
Home Bottle B has a higher temperature than Bottle A Bottle A Bottle A has 4 temperature units (16 ÷ 4 molecules = 4) Bottle B 10 Bottle B has 10 temperature units (10 ÷ 1 molecule = 10)
Home 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 ovens air (even though the air has a higher temperature). The ovens air is less dense than the pots water.
Home 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 matchs molecules. iceberg Zoom in of iceberg Zoom in of match match
Home See what youve 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 thats 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 temperature 3) heat and temperature 4) nothing A: heat and temperature Thats the end of this section. Click here to go home
Home Heat moves from hot objects to cold objects 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 heat heat heat heat heat Cup temperature Coffee temperature Lets add some hot coffee to the cup…
Home 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 finger heat 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.
Home Can you draw some arrows that show where heat will flow in this room? 212° 30° 42° 150° 72° 90° 375° 72° (air) 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° 42° 150° 72° 90° 375° 72° (air) 200° 130° 72° Heat will move from any warmer object toward any cooler object
Home Energy source An energy source is something that gives away energy; an energy receiver is something that takes energy Football Source (quarterback) Football Receiver ice finger heat Energy source Energy receiver heat
Home See what youve 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. warm cool 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 ______. heat icebook 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 ______. heat icebook Tomato 80°F Ice 20°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° Thats the end of this section. Click here to go home Energy source Energy receiver
Home 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 dont let heat pass through them easily C O N D U C T O R heat
Home Clothes do not give you heat; clothes keep you warm because they trap your bodys heat. heat My wool hat is a great insulator. Insulators dont let heat go through them. My bodys heat now stays with me. Brrrr – its freezing outside!
Home List of conductors and insulators Diamond 500,000.0 Copper 40,000.0 Gold 30,000.0 Aluminum 21,600.0 Concrete 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
Home See what youve 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 Alexis statement: I will put on my socks because my socks give me extra heat? A: Unless the socks are warmer than Alexi, they dont give him any heat. However, socks are good insulators; they trap the heat in Alexis feet and dont 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: Thats what. Circle all the objects below that are heat insulators: plastic metal cotton wood wool Thats the end of this section. Click here to go home